A long time ago the son of a deceased acquaintance of mine tried to sell the car of his father; wanted 3000.
Sent him a short mail: I'll give you 750 (imo 250 above market value), but take all the time you need to try to sell it for more than that, my bid will stand for at least a year.
Of course, his initial answer was that no way in hell he'd ever sell it for that kind of peanuts, he was insulted, such a unique car and blablabla, and I wished him respectfully the best of luck.
It took him just two months to get back at me and accept my offer.
My point being, that you have lots of sellers who don't have a clue about the true value of what they sell (and take it personally when s.o. points that out to them)
and you have lots of buyers who think they don't need to respect the seller, because they are the buyer, and therefore, by definition have the upper hand.
If you, either as a seller or a buyer, have to deal with any of those types, a transaction is likely to bounce off, leaving at least one party behind frustrated.