How much would i get if i sell these at gamestop?

I want to get rid of my psp silver 3000 and its 5 games. i dont want to wait and sell them on ebay. And i want to sell them at gamestop besides everyone else's opinions. the games are sims 2 castaway, national treasure:book of secrets, harvest moon: boy and girl, sonic rivals 2,ratchet and clank size matters, and final fantasy I. Then I also have 2 psp cases