While this looks wonderful, maybe too good, I'd advise:

1. Use escrow, at least until you earn some trust. As it is, anyone trying this "business" may risk to just "donate" you those bitcoin. I don't say that you want to scam, but you can do that too easy if you want to. So, again, consider using escrow (and learn how to use it so you also don't get scammed, obviously).

2. You should tell what country is this working for, or if it's restricted to internet purchases.

3. Consider avoiding to pay for services that may automatically turn into recursive payments.