Unwanted gift cards could be worth as much as 92.5 percent of their value on the secondary market, according to GiftCardGranny.com, a site that aggregates offers from various resellers. The more popular the retailer, the more you'll get. A card for gas station chain Chevron is worth as much as 91 percent at Junkcard.com, for example, or $22.75 for a $25 card. One for beauty brand Clinique is worth just 52 percent at GiftCardZen.com, or $13 for a $25 card.
Once you have an offer, most sale sites offer free shipping to send in the gift cards; you'll get a check within a week or two. In some cases, you can make the sale electronically by sending the gift card number and PIN, getting paid in a matter of hours.