beat sb down: to persuade someone to reduce a price 说服某人降价,杀价
He wanted $8 000 for the car but I beat him down to $6 000.
他那辆汽车要价8000元,但我压到了6000元.
Bargain: to discuss the conditions of a sale, agreement etc, for example to try and get a lower price 讨价还价,商讨条件
He said he wasn't prepared to bargain.
他说他不愿讨价还价.
Haggle: to argue when you are trying to agree about the price of something 讲价
通常搭配是: haggle (with sb) (over sth)
I left him in the market haggling over the price of a shirt.
我扔下他自己在市场上就一件衬衫讨价还价.