By default the user interface to enter per supplier product information is disabled. The user interface can be enabled or disabled at any point from Application Settings screen on the Product tab.
Scroll towards the bottom to the section named "Buying prices & reordering" Here you can choose to activate/deactivate the Product Detail fields for:
- Standard Buy Price
- Per Supplier Price
- Enable additional per supplier pricing fields (increases the default of 3 suppliers to 10 suppliers)