haggle
verb [ I or T ] uk/ˈhæɡ.əl/ us/ˈhæɡ.əl/
（对价格或条件）讨价还价
to attempt to decide on a price or conditions that are acceptable to the person selling the goods and the person buying them, usually by arguing
It's traditional that you haggle over/about the price of things in the market. 历来买卖东西时都会讨价还价。