Good advice here. You'll find plenty of work that needs to be done, even on a running, driving car. I spent a year working on my Challenger to get it running reliably enough to use it as my daily driver, and I still haven't addressed any of it's rust issues. And it was a complete, running car when I bought it.
I frequently see a-body's for sale, a lot of them are running cars. Nearly all of them cost under $6k, some a lot less, even for rust free running cars. I am in California, so most of the cars around here are pretty rust free, but it would be way more cost effective to pay to have a car shipped than pay $4k for a rust bucket.
If money is a big problem, look at 4 doors. I've seen VERY clean, running 4 door darts and valiants sell for under $2k.
