diff --git a/frontend/Entry.elm b/frontend/Entry.elm
index 34358b2..b410caa 100644
--- a/frontend/Entry.elm
+++ b/frontend/Entry.elm
@@ -135,11 +135,11 @@ updateState msg globals state = case state of
       case find (\tg -> tg.id == searchResult.taxGroupId) globals.taxGroups of
         Nothing -> (state, Cmd.none)
         Just taxGroup ->
-          ( ItemEditor
+          ( ItemEditor <| updateGrossUnitPrice
             { barcode = searchResult.barcode
             , name = searchResult.name
             , netUnitPrice = NumberInput.fromFloat searchResult.netUnitPrice
-            , grossUnitPrice = NumberInput.fromFloat <| calculateGarfieldPrice searchResult.netUnitPrice taxGroup.percentage
+            , grossUnitPrice = NumberInput.fromFloat 0
             , salesUnits = NumberInput.fromInt searchResult.salesUnits
             , group = Select.init (.id >> String.fromInt) (.name) { id = searchResult.groupId, name = searchResult.groupName } globals.groups
             , location = Select.init (.id >> String.fromInt) (.name) { id = searchResult.locationId, name = searchResult.locationName } globals.locations
@@ -175,7 +175,7 @@ updateState msg globals state = case state of
 
 updateGrossUnitPrice model =
   { model
-  | grossUnitPrice = NumberInput.fromFloat <| calculateGarfieldPrice (NumberInput.get model.netUnitPrice) (Select.get model.taxGroup).percentage
+  | grossUnitPrice = Maybe.withDefault model.grossUnitPrice <| Maybe.map NumberInput.fromFloat <| calculateGarfieldPrice model
   }
 
 -- View stuff
@@ -238,15 +238,23 @@ view { globals, state } = case state of
           [ label [ for "snack-name" ] [ text "Name" ]
           , input [ value model.name, disabled True, id "snack-name" ] []
           ]
-        , div [ class "form-input" ]
-          [ label [ for "gross-unit-price" ]
-            [ text <| "Stückpreis (Brutto), Vorschlag: " ++ String.fromFloat (calculateGarfieldPrice (NumberInput.get model.netUnitPrice) (Select.get model.taxGroup).percentage)
-            ]
-          , input [ onInput SetGrossUnitPrice, value <| NumberInput.show model.grossUnitPrice, id "gross-unit-price", type_ "number", step "0.01" ] []
-          ]
+        , viewGrossUnitPriceInput model
         ]
       ]
 
+viewGrossUnitPriceInput model =
+  let
+    suggestedPriceStr = case calculateGarfieldPrice model of
+      Nothing -> "?"
+      Just suggestedPrice -> String.fromFloat suggestedPrice
+  in
+    div [ class "form-input" ]
+      [ label [ for "gross-unit-price" ]
+        [ text <| "Stückpreis (Brutto), Vorschlag: " ++ suggestedPriceStr
+        ]
+      , input [ onInput SetGrossUnitPrice, value <| NumberInput.show model.grossUnitPrice, id "gross-unit-price", type_ "number", step "0.01" ] []
+      ]
+
 searchResultHeaders =
   tr []
     [ th [] [ text "Barcode" ]
@@ -275,8 +283,10 @@ viewSearchResult model =
       ]
     ]
 
-calculateGarfieldPrice netUnitPrice taxPercentage =
-  roundTo 2 <| netUnitPrice * (1 + taxPercentage) + 0.01
+calculateGarfieldPrice model =
+  NumberInput.get model.netUnitPrice |> Maybe.map (\netUnitPrice ->
+    roundTo 2 <| netUnitPrice * (1 + (Select.get model.taxGroup).percentage) + 0.01
+  )
 
 roundTo places x = toFloat (round <| x * 10 ^ places) / 10 ^ places
 
diff --git a/frontend/NumberInput.elm b/frontend/NumberInput.elm
index 6ffab83..f209dec 100644
--- a/frontend/NumberInput.elm
+++ b/frontend/NumberInput.elm
@@ -1,25 +1,29 @@
 module NumberInput exposing (..)
 
 type alias Model a =
-  { value : a
+  { value : Maybe a
   , original : String
   , convert : String -> Maybe a
   }
 
 fromFloat : Float -> Model Float
-fromFloat x = Model x (String.fromFloat x) String.toFloat
+fromFloat x = Model (Just x) (String.fromFloat x) String.toFloat
 
 fromInt : Int -> Model Int
-fromInt x = Model x (String.fromInt x) String.toInt
+fromInt x = Model (Just x) (String.fromInt x) String.toInt
 
-get : Model a -> a
+get : Model a -> Maybe a
 get = .value
 
+withDefault : a -> Model a -> a
+withDefault d = Maybe.withDefault d << get
+
+isValid : Model a -> Bool
+isValid model = model.value /= Nothing
+
 update : String -> Model a -> Model a
 update str model =
-  case model.convert str of
-    Nothing -> model
-    Just value -> { model | value = value, original = str }
+  { model | value = model.convert str, original = str }
 
 show : Model a -> String
 show = .original
diff --git a/jon/static/entry.js b/jon/static/entry.js
index 696f436..16b7f6b 100644
--- a/jon/static/entry.js
+++ b/jon/static/entry.js
@@ -10745,17 +10745,6 @@ var $author$project$Entry$ItemEditor = function (a) {
 var $author$project$Entry$ReceiveSearchResults = function (a) {
 	return {$: 'ReceiveSearchResults', a: a};
 };
-var $elm$core$Basics$pow = _Basics_pow;
-var $elm$core$Basics$round = _Basics_round;
-var $author$project$Entry$roundTo = F2(
-	function (places, x) {
-		return $elm$core$Basics$round(
-			x * A2($elm$core$Basics$pow, 10, places)) / A2($elm$core$Basics$pow, 10, places);
-	});
-var $author$project$Entry$calculateGarfieldPrice = F2(
-	function (netUnitPrice, taxPercentage) {
-		return A2($author$project$Entry$roundTo, 2, (netUnitPrice * (1 + taxPercentage)) + 0.01);
-	});
 var $elm$http$Http$BadStatus_ = F2(
 	function (a, b) {
 		return {$: 'BadStatus_', a: a, b: b};
@@ -10882,14 +10871,14 @@ var $elm$core$String$toFloat = _String_toFloat;
 var $author$project$NumberInput$fromFloat = function (x) {
 	return A3(
 		$author$project$NumberInput$Model,
-		x,
+		$elm$core$Maybe$Just(x),
 		$elm$core$String$fromFloat(x),
 		$elm$core$String$toFloat);
 };
 var $author$project$NumberInput$fromInt = function (x) {
 	return A3(
 		$author$project$NumberInput$Model,
-		x,
+		$elm$core$Maybe$Just(x),
 		$elm$core$String$fromInt(x),
 		$elm$core$String$toInt);
 };
@@ -11132,15 +11121,12 @@ var $author$project$Entry$searchResultDecoder = A3(
 											$elm$json$Json$Decode$succeed($author$project$Entry$SearchResult))))))))))));
 var $author$project$NumberInput$update = F2(
 	function (str, model) {
-		var _v0 = model.convert(str);
-		if (_v0.$ === 'Nothing') {
-			return model;
-		} else {
-			var value = _v0.a;
-			return _Utils_update(
-				model,
-				{original: str, value: value});
-		}
+		return _Utils_update(
+			model,
+			{
+				original: str,
+				value: model.convert(str)
+			});
 	});
 var $author$project$Select$find = F2(
 	function (pred, xs) {
@@ -11172,15 +11158,45 @@ var $author$project$NumberInput$get = function ($) {
 var $author$project$Select$get = function ($) {
 	return $.selected;
 };
+var $elm$core$Maybe$map = F2(
+	function (f, maybe) {
+		if (maybe.$ === 'Just') {
+			var value = maybe.a;
+			return $elm$core$Maybe$Just(
+				f(value));
+		} else {
+			return $elm$core$Maybe$Nothing;
+		}
+	});
+var $elm$core$Basics$pow = _Basics_pow;
+var $elm$core$Basics$round = _Basics_round;
+var $author$project$Entry$roundTo = F2(
+	function (places, x) {
+		return $elm$core$Basics$round(
+			x * A2($elm$core$Basics$pow, 10, places)) / A2($elm$core$Basics$pow, 10, places);
+	});
+var $author$project$Entry$calculateGarfieldPrice = function (model) {
+	return A2(
+		$elm$core$Maybe$map,
+		function (netUnitPrice) {
+			return A2(
+				$author$project$Entry$roundTo,
+				2,
+				(netUnitPrice * (1 + $author$project$Select$get(model.taxGroup).percentage)) + 0.01);
+		},
+		$author$project$NumberInput$get(model.netUnitPrice));
+};
 var $author$project$Entry$updateGrossUnitPrice = function (model) {
 	return _Utils_update(
 		model,
 		{
-			grossUnitPrice: $author$project$NumberInput$fromFloat(
+			grossUnitPrice: A2(
+				$elm$core$Maybe$withDefault,
+				model.grossUnitPrice,
 				A2(
-					$author$project$Entry$calculateGarfieldPrice,
-					$author$project$NumberInput$get(model.netUnitPrice),
-					$author$project$Select$get(model.taxGroup).percentage))
+					$elm$core$Maybe$map,
+					$author$project$NumberInput$fromFloat,
+					$author$project$Entry$calculateGarfieldPrice(model)))
 		});
 };
 var $author$project$Entry$updateState = F3(
@@ -11235,53 +11251,53 @@ var $author$project$Entry$updateState = F3(
 							var taxGroup = _v2.a;
 							return _Utils_Tuple2(
 								$author$project$Entry$ItemEditor(
-									{
-										barcode: searchResult.barcode,
-										grossUnitPrice: $author$project$NumberInput$fromFloat(
-											A2($author$project$Entry$calculateGarfieldPrice, searchResult.netUnitPrice, taxGroup.percentage)),
-										group: A4(
-											$author$project$Select$init,
-											A2(
-												$elm$core$Basics$composeR,
+									$author$project$Entry$updateGrossUnitPrice(
+										{
+											barcode: searchResult.barcode,
+											grossUnitPrice: $author$project$NumberInput$fromFloat(0),
+											group: A4(
+												$author$project$Select$init,
+												A2(
+													$elm$core$Basics$composeR,
+													function ($) {
+														return $.id;
+													},
+													$elm$core$String$fromInt),
 												function ($) {
-													return $.id;
+													return $.name;
 												},
-												$elm$core$String$fromInt),
-											function ($) {
-												return $.name;
-											},
-											{id: searchResult.groupId, name: searchResult.groupName},
-											globals.groups),
-										location: A4(
-											$author$project$Select$init,
-											A2(
-												$elm$core$Basics$composeR,
+												{id: searchResult.groupId, name: searchResult.groupName},
+												globals.groups),
+											location: A4(
+												$author$project$Select$init,
+												A2(
+													$elm$core$Basics$composeR,
+													function ($) {
+														return $.id;
+													},
+													$elm$core$String$fromInt),
 												function ($) {
-													return $.id;
+													return $.name;
 												},
-												$elm$core$String$fromInt),
-											function ($) {
-												return $.name;
-											},
-											{id: searchResult.locationId, name: searchResult.locationName},
-											globals.locations),
-										name: searchResult.name,
-										netUnitPrice: $author$project$NumberInput$fromFloat(searchResult.netUnitPrice),
-										salesUnits: $author$project$NumberInput$fromInt(searchResult.salesUnits),
-										taxGroup: A4(
-											$author$project$Select$init,
-											A2(
-												$elm$core$Basics$composeR,
+												{id: searchResult.locationId, name: searchResult.locationName},
+												globals.locations),
+											name: searchResult.name,
+											netUnitPrice: $author$project$NumberInput$fromFloat(searchResult.netUnitPrice),
+											salesUnits: $author$project$NumberInput$fromInt(searchResult.salesUnits),
+											taxGroup: A4(
+												$author$project$Select$init,
+												A2(
+													$elm$core$Basics$composeR,
+													function ($) {
+														return $.id;
+													},
+													$elm$core$String$fromInt),
 												function ($) {
-													return $.id;
+													return $.description;
 												},
-												$elm$core$String$fromInt),
-											function ($) {
-												return $.description;
-											},
-											taxGroup,
-											globals.taxGroups)
-									}),
+												taxGroup,
+												globals.taxGroups)
+										})),
 								$elm$core$Platform$Cmd$none);
 						}
 					default:
@@ -11389,9 +11405,6 @@ var $author$project$Entry$update = F2(
 var $author$project$Entry$SetBarcode = function (a) {
 	return {$: 'SetBarcode', a: a};
 };
-var $author$project$Entry$SetGrossUnitPrice = function (a) {
-	return {$: 'SetGrossUnitPrice', a: a};
-};
 var $author$project$Entry$SetGroup = function (a) {
 	return {$: 'SetGroup', a: a};
 };
@@ -11553,6 +11566,51 @@ var $author$project$Select$view = F2(
 				]),
 			A2($elm$core$List$map, viewOption, model.options));
 	});
+var $author$project$Entry$SetGrossUnitPrice = function (a) {
+	return {$: 'SetGrossUnitPrice', a: a};
+};
+var $author$project$Entry$viewGrossUnitPriceInput = function (model) {
+	var suggestedPriceStr = function () {
+		var _v0 = $author$project$Entry$calculateGarfieldPrice(model);
+		if (_v0.$ === 'Nothing') {
+			return '?';
+		} else {
+			var suggestedPrice = _v0.a;
+			return $elm$core$String$fromFloat(suggestedPrice);
+		}
+	}();
+	return A2(
+		$elm$html$Html$div,
+		_List_fromArray(
+			[
+				$elm$html$Html$Attributes$class('form-input')
+			]),
+		_List_fromArray(
+			[
+				A2(
+				$elm$html$Html$label,
+				_List_fromArray(
+					[
+						$elm$html$Html$Attributes$for('gross-unit-price')
+					]),
+				_List_fromArray(
+					[
+						$elm$html$Html$text('Stückpreis (Brutto), Vorschlag: ' + suggestedPriceStr)
+					])),
+				A2(
+				$elm$html$Html$input,
+				_List_fromArray(
+					[
+						$elm$html$Html$Events$onInput($author$project$Entry$SetGrossUnitPrice),
+						$elm$html$Html$Attributes$value(
+						$author$project$NumberInput$show(model.grossUnitPrice)),
+						$elm$html$Html$Attributes$id('gross-unit-price'),
+						$elm$html$Html$Attributes$type_('number'),
+						$elm$html$Html$Attributes$step('0.01')
+					]),
+				_List_Nil)
+			]));
+};
 var $author$project$Entry$GotoItemEditor = function (a) {
 	return {$: 'GotoItemEditor', a: a};
 };
@@ -11955,42 +12013,7 @@ var $author$project$Entry$view = function (_v0) {
 										]),
 									_List_Nil)
 								])),
-							A2(
-							$elm$html$Html$div,
-							_List_fromArray(
-								[
-									$elm$html$Html$Attributes$class('form-input')
-								]),
-							_List_fromArray(
-								[
-									A2(
-									$elm$html$Html$label,
-									_List_fromArray(
-										[
-											$elm$html$Html$Attributes$for('gross-unit-price')
-										]),
-									_List_fromArray(
-										[
-											$elm$html$Html$text(
-											'Stückpreis (Brutto), Vorschlag: ' + $elm$core$String$fromFloat(
-												A2(
-													$author$project$Entry$calculateGarfieldPrice,
-													$author$project$NumberInput$get(model.netUnitPrice),
-													$author$project$Select$get(model.taxGroup).percentage)))
-										])),
-									A2(
-									$elm$html$Html$input,
-									_List_fromArray(
-										[
-											$elm$html$Html$Events$onInput($author$project$Entry$SetGrossUnitPrice),
-											$elm$html$Html$Attributes$value(
-											$author$project$NumberInput$show(model.grossUnitPrice)),
-											$elm$html$Html$Attributes$id('gross-unit-price'),
-											$elm$html$Html$Attributes$type_('number'),
-											$elm$html$Html$Attributes$step('0.01')
-										]),
-									_List_Nil)
-								]))
+							$author$project$Entry$viewGrossUnitPriceInput(model)
 						]))
 				]));
 	}