How much could I get for a car running on 3 cylinders instead of 4?

That's pretty high mileage and pretty old, plus it has defects (engine and back hatch). You might find some high school kid who just got his license who'd be willing to give you a couple of hundred bucks for it. Especially if he took (or is taking) auto mechanic cles. Put it up on Craigslist or in your local freebie newspaper and see what happens.