Reselling at Gamestop means you don't have to worry about
PAYPAL fees on top of EBAY fees.
And unless you are lucky enough to force the buyer on E-bay to fork over 100% the total cost of Shipping & Handling & Packaging...You have to consider what you might end up losing by going through all that.
Plus, the long wait time you may have to sell something on e-bay.
I tried selling on E-bay before...I never sold the item cause there were no buyers.