Selling anything to Gamestop is bad.Selling your electronics to a company like GameStop is basically willfully enabled theft. You'd probably get more just sending it to eBay for their valet service.
And honestly its not even Gamestop's fault. If you do it, you seriously need to get checked out. Maybe some are rich and don't care they are getting ripped off, but then you wouldn't even need to trade in your old devices.
RIP those people. I hope one day they realize you can literally get like 10x amount anywhere else.