Depending on the game, some of those old 2600 carts can be worth major bucks. I kept my old Imsai 8080 just in case and now its quite a collector item.
I'll have to check, I do have an old pac-man and Laser Blast, not sure about the rest.
What about carts to work on Atari 800s (don't think they work on anything else, but don't know)? I have Miner 2049r, Pac Man, Space Invaders, Missile Command, others, all working, as does computer (1982 vintage).