How to deal with customers constantly bargaining and finally wiping out zeros?

In the face of customers constantly bargaining and finally wiping out zeros, we can choose to put a banner on the wall with no counter-offering. We believe that customers will not choose to bargain again after seeing it. And wipe zero.

My friend used to sell some things. His customers always kept bargaining and finally asked for zero. He was very distressed about this and always had a long stalemate with others. Later, I suggested that he put a no-haggle banner on the wall, which could effectively prevent customers from haggling. He tried my method and it was really effective. Since then, there have been very few customers. Customers no longer asked him to bargain or wipe out zeros.