Did you try on posting on purse.io? I believe I got a 30% off amazon wishlist funded over there, but I'm not sure about the activity of the buyers there anymore. Good Luck!
saw the last completed orders there.....its like 10-12%.....they just advertise 25%
You need to use escrow. Otherwise no one will give you any order! Also, since you say you have made some altcoins, you should name a few successful ones if its true!
AMAZON cards can be charged back even after you successfully redeem them! Using an escrow won't help in that case. My advise: Stay away from buying amazon gcs from new/untrusted accounts.