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).
I am not sure. I do know old computers are becoming major collector peices. I would hang on to it. I have about 9 pre 1980 computers myself.
I don't know what Atari 800 games are worth, but I'm not sure these old carts are exactly a goldmine anyway. I saw a list of Atari and Coleco cartridges, and I had quite a few that were considered "ultra rare." They could net something like $35. To me, that's not worth losing cartridges I've had for years. I'll hold on to them.