Trading these games to get Modern Warfare 2 wanting to know how much would I get?

i dont know were u from so not sure how much this may help but i recently traded call of duty waw at games station and got �14 for it,on the way out the shop i noticed they were selling it pre owned for �32. so using this as a guide if u go into the shop your trading at, look at the pre owned prices of the games your trading and ul get just under half that price 4 it lol