and what he gets are two independent points. The buyer and the market determine the actual sales price.
You can't take it personally that a seller gets it into his head that his car is better than all those other cars and so he should get more for his. Or a dealer wants to make money. It is just human nature.
Could edmunds be getting prices from actual state registrations? I know I've gotten 20% difference between pricing providers when I priced a car in the past.
Look at these few for a comparative set of prices.
http://www.motorcarinvestments.com/
I just stumbled on them today recommended by a Raleigh owner.