I have a bit different slant on the buying/selling relationship.
The owner knows what he will take for the airplane and the buyer knows what he will pay. If the owner makes an offer to sell at a stated price I think that it is up to the buyer to make a legitimate offer to buy It is then up to the seller to decide whether or not he is willing to accept the offer.
I have had a number of people call and ask a few questions then ask if I am flexible or the price or what my best price is. They haven?t even looked at the airplane and already they want to dicker. My standard answer is ?What are you willing to pay?? I have yet to get an answer. I don?t figure that they have the right to essentially say ?I know that you are lying about the price, now tell me the truth?, I immediately write them off as tire kickers and forget about them.