One auction? You would do better to list 3 with the Atari in one the GBC in another and the PS2 stuff, just works out better that way most times. But who knows you might get lucky someone looking for a starter set of 2600 stuff & a GBC, yours is probably the only auction on ebay.
But if it doesn't sell, you might want to do separate auctions for it next time around. Actually I would sell the Gremlins cart separate too, if the front label is good it would bring $10-15 by itself.
Also if you took the time to complete the Atari so that it was tested & working it'd probably be more apealing to bidders as well. All you would need is a rca cable & a
F-type to female rca adapter Which you can pick up at a radio shack for cheap. For controllers you can use a Sega Genesis pad. May not look like a great setup, but it would work for you.
As it is now thou, you have a piece of Atari with some mostly common games, maybe $30 tops total, and a defaced GBC without pix, and one common used PS2 game. Maybe around $50 for the lot in it's current state. And you have a reserve above that.

But it
is ebay, so who knows!

Good luck to you!
