Guitar Hero World Tour

i want to know how much store credit i would get at gamestop if i traded in these games:
killzone 2
prototype
motor storm ( the first one )
guitar hero smash hits
need for speed undercover

Also im thinking about trading in cod 4 and cod 5… so if i were to trade those in as well how much would i get? Im more interested in the amound i would get for the tope 5 games. but if oyu dont mind, i would like a price for either option
thanks in advance