Where a car is sold has a direct effect on its price. The "buy on Craigslist, sell at auction" maxim has been used by traders for years, and an examination of average price across channels for a 1965 Ford Mustang confirms this hierarchy. Interestingly, though, the gap between auction prices and listing prices has tightened dramatically over the past 24 months, with FSBO prices now nearly two-thirds what auction prices are. This figure was just 25% in 2013.
The cause is multivariate, but the gap in quality between what sold privately and what sold at auction has closed since 2012, at least as far as the Mustang is concerned. More Mustangs in "excellent" condition are coming through the private sales channel than before, while more Mustangs in less than excellent condition are now frequently found at regional and smaller auctions than they were in 2013. Venue is important, but you can't forget about condition.