Here's one for $20k.
https://classics.autotrader.com/clas...bird/101254543
Really nice ones are probably at least twice that.
Guessing that most project cars, under $10k are probably rust buckets. Otherwise they would have already been restored.
https://classics.autotrader.com/clas...bird/101121087
https://classics.autotrader.com/clas...bird/101234892
https://classics.autotrader.com/clas...bird/101257961
https://www.ebay.com/itm/1967-Pontia...8AAOSwhqFeQMRe
Here's a Chevy powered hot rod. But, if the body is clean, at the price, he may be able to sell the engine, then partially pay for a decent Pontiac engine.
https://classics.autotrader.com/clas...bird/101268421
Sometimes you run across ads that are probably bogus, or the car was sold years ago. Never know what you'll find online.
https://usclassifieds4all.com/detail...listing=175931
https://www.easyautosales.com/used-c...-69166882.html
But, hey, he can always hope for a "barn find" like we use to read about.
So, what's his aprox budget, for a decent driver ?