I once advertised a car for sale cheaply, I think it was £250, I just wanted to get rid. A chap rung me and asked if I would take £225, I said yes but that was the lowest I would go, so don't expect to arrive and haggle.
So he and his mate turn up. They want it for less, I say no and walk away. He then says he will have it but he does not have enough money for the petrol home, they was probably 40 miles worth in the tank. I say that's not my problem and go off in to the house. He then come back and says he only has change, I say that's fine, I could do with change. So he literally went through his and his friends pockets looking for money down to 10pand 20p, which I counted out and took to make the full amount.
They came never expecting to pay the full amount, who go to look at a car with no money for petrol, because in my experience the petrol station is your first stop after the money changes hands.
When I am buying I tend to only look at things I know I can afford and would only make and offer if I really thought it was over priced. I explain my reason and leave the offer for them to think about. I once had to wait two months.
A good sale is when the buyer and seller are both happy. Sometimes I have perhaps paid too much, but I have really wanted it, and the trailing round for something right is not a hobby for me.