How is it that you acquire these gift cards below face value? Perhaps disclosing that would help alleviate some of the trust issues with taking you up on this offer.
I take advantage of various rebate offers to get better-than-normal deals, but my ongoing deal is from American Express Gift Cards themselves. I subscribe to them to receive free shipping. My frequent customer status causes them to send me waivers of the purchase fees. I also purchase them through a seller than offers a partial rebate of the commission that American Express gives. As such, I can get them shipped somewhere or e-mailed to someone for slightly below face value with no fees.
As for other gift cards, if I can't get a better promotional deal on one of those, I could always just buy an American Express gift card, then use that to buy the gift card the person wishes to buy.
The 1% represents most of the commission rebate that I'm receiving. I offer it to buyers in Bitcoin as an incentive to go through me instead of going through an exchange if their ultimate goal is to simply cash out Bitcoin to buy something in USD.