Trade ins on financed cars?

I'm trying to get rid of my 2003 RS Eclipse, it's got some work done to it, but I owe $3,800 on it with Carmax. Had it for 2 years and now I'd like to trade it in and get myself something 5 speed. My credit is garbage due to school loans and I just got a new job about 4 weeks ago so I'm basically stuck with Buy Here Pay Heres unless I find a cosigner. I don't have money to put down on another car, another reason I want to trade it in, but I can afford a good bit in monthly payments. I attempted to sale it outright but that is taking alot longer than I'd like and admittedly my patience is low - I want to get it out of my hands within a week or 2.

So, does anyone know of any Buy Here's in north georgia that accept trade ins on cars that have existing balances on them? Or at least what that whole process involves? I'm not too sure im "upside-down" per se, since according to Black book and KBB my car is worth about $4000 based on what I have done to it and its condition. Though it's worth about 1300 in trade value to dealerships apparantly. I figured I'd ask the legit car community what the best option would be since most dealers will either lie to me or just go by the book and turn me down before letting me ask questions.

This is not an advertisement - I've got that taken care of. I just need some advice on how to get the car out of my hands sooner than later and have another car the same day. I'm willing to take the financial loss and could care less about making a profit.

Thanks