3 sentences

1. 爱情是不可以讨价还价的。

   ài​qíng shì bù kě​yǐ tǎo​jià​huán​jià de.

   Love is not negotiable.

   Source: OpenSubtitles

2. 在原则问题上，我们绝不讨价还价。

   zài yuán​zé wèn​tí shàng, wǒ​men jué bù tǎo​jià​huán​jià.

   We never compromise on matters of principle.

   Source: Dong Chinese Dictionary

3. 买衣服时，她总是喜欢跟老板讨价还价。

   mǎi yī​fu shí, tā zǒng​shì xǐ​huan gēn lǎo​bǎn tǎo​jià​huán​jià.

   She always likes to haggle with the shopkeeper when buying clothes.

   Source: Dong Chinese Dictionary