Negotiation is the inverse of tipping.
Akimoto Suzutomo, a wealthy adherent of the tea ceremony, once gave his page 100 ryo (gold pieces) and instructed him to purchase a tea bowl offered by a particular dealer. When the page saw the bowl, he doubted it was worth that much, and after much bargaining got the price reduced to 95 ryo. Days later, after Suzutomo had put the bowl to use, the page proudly told him what he had done. “What an ignoramus you are!” replied Suzutomo. “A tea bowl that anyone asks 100 pieces of gold for can only be a family heirloom, and a thing like that is only sold when the family is pressed for money. And in that case they will be hoping to find someone who will give even 150 pieces for it. So what sort of fellow is it who does not consider their feelings? Quite apart from that, a curio that you give 100 ryo for is something worth having, but one that has only cost 95 gives a mean impression. So never let me see that tea bowl again!” And he had the bowl locked away, and never took it out.
Turns out that commercial transactions happen in a social context, and even when it doesn't come back to bite you financially, sometimes paying less has social costs that are far higher than what you "saved".
If the buyer displays the item, then elite of Feudal Japan will say "Poor so and so, they got taken advantaged of by a merciless nouveau riche. Make sure not to invite that person to our upper class parties. We may be poor compared to them; but we still have our samurai pride."
Edited for spelling.
In this case, the listed price is the floor price, even though the seller agreed to less in the end. The expected price was unlisted.
With tipping, the floor price is actually higher than the listed price. Someone might agree to sell at a lower price, but below that floor price, it brings great dishonor.