导购口语:

As you have made many other purchases, I will take off ten percent from the price on the tag.
既然您买了很多其他东西，我就照定价给您打九折。
There is only a discount if it is a triple purchase.
只有购买三件套才会有折扣。
I'll bring the price down to 30 dollars a piece, if you make a big purchase. What do you think?
如果您打算大量购买，我就把价格降到每件30美元，怎么样？

语句解析:

Take off ten percent 打九折，take off 在这里不是“起飞”的意思，而是表示“扣除，减价”；bring the price down to…把价格降到……；bring down 意为“降低，减少”；make a big purchase 大量购买。

情景再现:

They wanted to charge 5000 dollars for the car, (but) we managed to bring the price down.
他们这辆车要价5000美金，但是我们把价格谈下来了。
The more you buy, the more you save.
买的越多越划算。