Try craigslist or your local newspaper classified ads.

ignore what blue book says. the vehicle is only worth what someone is willing to pay for it. and as cars get older and crappier, the more variance you'll have. take your $1000 to a private party and beat them up on price. wave the money around, let the seller smell it, do whatever it takes. Give them a sob story. Get on your knees and beg. And always point out the facts, your have cash with you right now. If they don't want to budge, go to the next guy, wash, rinse repeat. You'll fetch the best deal via private party. Make sure to go over the car with a fine tooth comb and point out ever little deficiency.

good luck. and don't forget about TTL.

If you don't know much about cars, take someone with you that do especially a mechanic.

Ask for service records or what they have done on the car recently.

In college I bought a car for $1,000 cash. I requested that the sale be contingent on my (trusted) mechanic looking the car over before things were final. (As I recall, the purchase price was more like $1,100 but my mechanic found $100 worth of repairs that needed doing so that was knocked off the purchase price.) I drove that car for 2+ years in college, and only bought a new one after I graduated because the car leaked so I would get rained on during/after any precipitation. Otherwise the car ran fine, had well under 100k miles, and was in pretty good shape.

I did the same thing. Got a steal for an economy vehicle for $6000 cash. I used it for 4-5 years before I bought my first new vehicle. The car had leaked when it rained eventually and I determined it wasn't worth fixing. Plus I got it with 47k miles on it. By the time I replaced the vehicle it had almost 100k.