You gotta call them up and ask how much credit they'll give for each individual game. It depends on the game itself. If you're looking for pocket change, I doubt you'll get much out of it. You're probably better off getting store credit for your games.
not that much ps2 game probably go for like $5 each since they are old and have to make the money back. no one now a days really buys ps2 games also.
I dont think they give you cash usually they give you store credit.
Ps- if you dont know what store credit is. it's like virtual cash you can ONLY spend at gamestop. no where else. you can try ask for cash but im not sure they will allow it. sometimes they gave me cash that was like only 1 time though.