How much will gamestop give me for these games ?

mario party 8,mario kart wii,mario strikers charged,my baby girl,disney friends,pokemo soulsliver,kingdom hearts 358/2 days,kick *** umd movie,gardening mama,pawas and claws pampered pets,build a bear workshop, i think i have like two more but just tell me and dont tell me to go to ebay or craigs list okay tell me an estimated amount , in a few days starting in july 1 they are giving 40 percent more but its 50 for me because i have power up card pro please tell me