You say 'getting greedy', and I say 'getting out of competition with credit/debit card thieves who can offer Amazon purchases for almost any discount and still profit with near-zero expenses'...
Let's call the whole thing off!
People who are used to getting massive discounts that thieves offer like to call honest retailers "greedy" for trading for a tiny margin (if any). I have even been accused of being a scammer for selling a gift card at face value (because con artists offer it cheaper elsewhere). People like you (op) are the reason people like me don't sell gift cards any more.
I advertise my gift cards at face value, I wouldn't say they never get sold. It just takes a while and you have to hustle when people put up WTBs for gift cards & proxy purchases.