There's a fellow in Dallas who specializes in fixing up and reselling classic mountain bikes. Prices seem reasonable if the bikes are as good as they look from his ads.
And I see a lot of beaters in the D/FW area. Folks drag those bikes out of storage neglect and usually sell 'em as-is. Most of those bikes look like they'd need upward of $100 in parts and work to get back to riding condition.