Arguing or negotiating the price of something can be called "haggling". When you're a customer, you haggle to get the seller to reduce the price of an item.
The word "haggle" sounds pretty negative. If you say that someone is "haggling", it makes them sound cheap and greedy.
Here are some other examples of the different ways that "haggle" can be used in a sentence:
I don't have time to haggle with you.
I don't have time to haggle over the price of a piece of furniture.
I don't have time to haggle over a piece of furniture.