This is an Atari 2000. It is a prototype Atari system that was supposed to come out before the Atari 2600 jr. There were only a few that were made and those were snapped up by Atari employees. The guy who is selling this doesn't really want to sell it. He is just getting some cheap advertising for the East Coast Gaming Expo.
btw, I didn't know all of this, they have a similar topic up on Atari Age.
Just figured I'd come clean on my knowledge thaft.