Bitmit's escrow is fairly reliable- you send your payment and it stays locked up and then I send you the code, and once you have it working and are happy with it, you just release your payment on your own time to my wallet; just like any other escrow system. I know that giftcards never sell at full price because there is a lot of speculation about whether or not it has been stolen, so to make sure buyers can be assured they're legit from me, I take pictures of the physical card (I buy them at the store) and I can also send pictures of the receipt.
I've sold this card but will have another very soon that I'll be trying to sell again.
Thanks all!