Just use the gift card to upgrade to something better.
Turn in an RG-14 you paid $50 for $200, and buy a Hi-Point 9 mm.
Or turn in an old .22 semi-auto with a detachable magazine, and buy a used Glock.
Lots of possibilities, but those who want to make a profit will have to be quick, because I expect the money will be gone before noon.
Jimenez and Pheonix Arms 22 handguns are around $100