I have never sold gift cards to any of the sites, but I have purchased from several of them. My favorite to purchase from is Cardpool and I would say they are very reputable. What stores do you have that you want to sell? The price offered will vary a lot. It also seems that gift cards can sell well on eBay, but I am not sure if that is a great place for sellers given the overwhelming inclination towards favoring buyers if there is a dispute.