A body value

I see people asking a lot of money for cars these days, but what are they really selling them for?
A guy on craigslist had a 1974 duster that needed work, he was asking $6500 for it and wouldn't take offers I don't know what he got for it but I do know that he had it for sale for 4 years. I offered him 6k and he said no. I bet that he got less than he was asking for it