Boss Rods,
Welcome, and glad to see you here. Your statement is,
It would need to be street worthy from the get go, and be a good candidate for investing the time / $$ to take to shows in a few yrs. of weekend rebuilding.
A basic roller package from N&N is $13,200 (new chassis, glass body, Pete & Jakes chassis components) and unless you're buying wholesale you'll more than double that to build from scratch, not counting paint and interior. So you're looking for a seller who's put $30K or more into his ride, wanting to sell it for 1/3 or much less. Now that's not to say that you might not run across that one guy who's gotten into money problems, has to have cash quick to keep the wolves at bay, and is selling his toy at deep losses, but even then I'd be surprised to see anything below $25K for a running, driving car of any quality.

Like Glenn says, don't give up the dream, but spend some time looking around and get a handle on the reality of the pricing, then start figuring how to structure your "deal". Good luck!!