I say PS3 but hold on it a bit like some have said "there might" be a price drop on it or not but look at it this way you only have to pay for it once.
Also if your interested in the PS2 series of games the original 20/60 GB systems are compatable with all 3 generations of Playstation. Plus like you stated your friends own a few PS3 games maybe you could borrow a few single player ones they have or get your own copy(or rent)and play with/against them online.
Also if your interested in the PS2 series of games the original 20/60 GB systems are compatable with all 3 generations of Playstation. Plus like you stated your friends own a few PS3 games maybe you could borrow a few single player ones they have or get your own copy(or rent)and play with/against them online.