The guy who bought it for $500 was just a kid who knew what the car was. The used car dealer didn't have a clue what was sitting on his lot.

When I was just out of high school I bought a 1969 Torino Cobra Jet off a used car lot for $500. Had a 428CJ and a four speed. I knew it was worth more than $500 so I grabbed it. It wasn't worth $2M like this car, but it would be worth $40K or so these days if I had kept it.