Summary:
When submitting your app to the Underground program, you should still set a list price for your IAP items. This way users will understand the value they are receiving through the Underground app.
However, please be aware that while the Amazon IAP UI will automatically show a price strike through, this will not automatically occur on any custom IAP price list in your app’s UI. If you would like to show a price strike through, similar to what is shown on the Amazon IAP UI, you will need to manually include this in your app.
