Mirror that's a great idea, take the money as an Amazon voucher. I spend shit loads on Amazon!
The only reason I accepted my guy was because I'd seen him multiple times before. He's a fucking idiot because he knows how good my service is and now he's never gonna get it again.
Yes the cards can be bought in even quite small places and small shops.
Do be aware if bought online there can be a delay, some come through immediately, some take anything from 1 - 12 hours (although I heavily suspect the 12 hour one hadn't been sent, until I advised the booking wasn't confirmed until the card was received and applied to my account).
Once again don't accept screen shots, you need to have received the email and apply it to your Amazon account. Also don't click on the automatic 'thank you' unless it's in your work name and work email address only - because it will go with whatever details/name you have on your Amazon account.