Please explain how and why you buy the cards. Do you use your own (legal) money to buy these gift cards? You're saying you buy them from Amazon and AFAIK they sell at the face value. If you buy this way why do you sell at a discount price? Do you also buy BTC directly with cash skipping the step where you buy the cards and lose the given discount?
no matter the answer he could give, we all know the answer --
assume that these are not legitimate. even honorable sellers that believe they may be purchasing legitimate cards often are not, and are passing off carded items.