Yaar exchanged alot of games.. Just recently i exchanged Uncharted and Dirt for GTA 4.. Currently i have Fifa 09 and Fifa 08, Gta4, MGS4 and GT5.. I had Resistance, Motorstorm and 3-4 more games but i exchanged them.. The cost of the game depends on the individual games and if they are new or not.
I usually order from play-asia.com or yesasia.com .. Most of the games there cost around 40-60$.. People here in pakistan sell games really expensive if its just released so i order it from that website.