Thanks for the advice guys!
I've done some more research and have come to the conclusion it really doesn't matter which model I go for. Atm I don't have a laptop (which isn't all that bad, because I should be studying for finals anyway) but I want one soon.
Another advantage of the 2011 13" is the thunderbolt port, which I think will come in handy once thunderbolt becomes more common.
I'm probably going to pick up a 13" 2011 MBP tomorrow for 150€. I guess that's the right way to go. A 2010 15" would be too.
Won't probably be too expensive by then, ha!
