Thank you very much guys! If you don't mind I'll wait a little bit and see what I can find on ebay, but I'll have in mind your offers!
At the time I have the 32 in 1 (great game, a must-have in my opinion), Golf, Phoenix, Mouse Trap, Frostbite, Dodge 'Em, Super Breakout, Berzerk, Pac-man, Asteroids, Combat and Defender. Some of them are crappy and others don´t have stickers or are mising the end label. The ones I am proud of are the latest 4, as they are in their original boxes with manuals and all (I managed to get them along with the 2600 and its box, plus two joysticks, paddle controlers and AC adapter, all for 50 euros). However, I'd like to get the "classics". Games such as Pitfall, Vanguard, Donkey Kong, Centipede, ET (yeah, I know... ) and similar.