Like the others, I recomend against selling. When I was in highschool I got rind of my Atari games and latter regreted(spelling?) it a lot. Becasue of that, I had to spend a lot $$$ to get some of that stuff back.
Now I am 29 and by no means I am giving up my Atari! Even if it's just sitting there taking dust, I still have it in front of my TV ready to play.