I don't want to use data, as I have a gophone, and last I checked, using data costs a whole buttload of money. ( I wanna get Minecraft, and I want to charge straight to my at&t account.)
If you have a GoPhone Account it would not support Carrier Billing in the store. That is up to the Carrier, not the Windows Phone App Store. So far as I know there are no airtime resellers (which GoPhone is) that allow Carrier Billing... You are on prepaid and only get what you paid for up front... Carrier Billing is a PostPaid situation where a bill comes for what you've done the past month.