Fix for displaying a negative price for a custom option. Currently a negative price is displayed as +- 5.00 for instance. By changing the template to check of the value is actually positive a negative value will be displayed as - 5.00 and a positive value will be displayed as + 5.00

Author: dverkade

app/code/Magento/Catalog/view/base/web/js/price-options.js

@@ -19,8 +19,10 @@ define([
         optionConfig: {},
         optionHandlers: {},
         optionTemplate: '<%= data.label %>' +
-        '<% if (data.finalPrice.value) { %>' +
+        '<% if (data.finalPrice.value > 0) { %>' +
         ' +<%- data.finalPrice.formatted %>' +
+        '<% } else if (data.finalPrice.value < 0) { %>' +
+        ' <%- data.finalPrice.formatted %>' +
         '<% } %>',
         controlContainer: 'dd'
     };