That's trickier. Amazon owns the payment flow on that product.
They'll get what they expect. They expect a credit card transaction. Every bitcoin purchase on the front end will trigger corresponding credit card transaction on the back end. This will be the credit card of web store owner.
Amazon controls the payment experience, including client side AFAIK - there is no "back end" to trigger a CC transaction. It sounds like a good idea but I don't see how its feasible.
In any case, if anyone thinks that an AWS bitcoin purchasing app has legs let me know, i'll probably just start doing some simple MVP work, but if there is more interest I'll ramp it up quicker.