A question about Call of Duty MW2 and Steam...!?

Game and gamestation are selling mw2 NEW for �30 now. So used be a bit less. You cant do it for some games cause of copy rights but why don't you get a usb stick transfer your file from your friends ps3 then upload it on to your ps3. Like i said not all game can do this not sure if mw2 is one or not check the game manual or try it.