Police or bank auctions are amazing, especially if you're a person who can look at a car and know what's going on under the hood. Heck, I even like going to police auctions to pick up other stuff - they have everything.
I'd say for $5K you can find something pretty nice - perhaps a late model Caddy from some drug dealer with an ounce of coke under the back seat
You'll definitely find something to make the trip worth your while. If anything, get a cheap fixer-upper for a couple of hundred. Even if you can't fix it, you could part it out and make some dough.