There is also the issue that a lot of owners do not want to deal with today's buyers. Just look at the aggravations often cited here when it comes to selling just a few parts. Selling a big ticket item is just such a hassle in most cases where the seller wants to get all he can. Then there is the issue of guaranteeing the funds and maybe the quality of the title. Issues that a lot of guys just aren't fluent in and are rightfully concerned about getting screwed in the process.

This is not a recommendation for or affirmation of 'classic car dealers', it is just a few more reasons for their existence.