I know when that happens, it really sucks, and I think he went about it in the wrong way. He should have corrected the ad, or pulled it and put a new ad out. But it's his car, and he can ask whatever he wants for it. I'm sure that most people, if they were told that something they are selling is worth more than they are asking, would correct their price. It's only human nature.
Put your self in his shoes. Lets say that you have a NOS 71 Cuda grill that you decide to sell, and you dont know what its worth. You advertise it for $200. One of your good CCC buddies, says "Hey, those grills are going for $3k on eBay". What would you do? Sell it to somebody for $200 because they saw your ad, and lose $2800, or sell it on eBay?
I think that you are letting emotion or principle affect your judgement. I mean, dont let the fact that he advertised it for 17 and now wants 20 stop you from making a good deal. Look the car over. If you think its worth the 20, and you have the money, buy it. If you dont think its worth it, or you dont have the money, offer him what you are willing to pay, and leave your phone number.
If he sells it to someone else, then you didnt lose anything, because to you it wasnt worth it.
If no one meets his price, he'll get tired of sitting on it, and might take you up on your offer. Just bug him about it every couple of weeks to let him know you are still interested, and in case he loses your number.
