Depending on the games/condition - I'd think it would be worth about $60/$70 so $50 would be a solid offer. Thats just my opinion though for what its worth.
Indeed, it totally depends on the games and condition, but if I had to say something based off that info alone...um...$55 or 60, at least, but that could go up a lot, depending on the games and condition.
Depends on the games and depends on where you live... you couldn't sell a Genesis system where I am for more than $15-20 is you're lucky, seeing as they're everywhere around here.