怎么回复喜欢砍价的美国老外？大家帮帮忙啊！

这个美国老外是通过谷歌搜到的，之前有和他了一段时间！我们是石材玉石的，大板厚度都是1.8cm，但是对方要求一定是2cm. 那时候他是想下一个柜子的单子，但是卡在这个尺寸上就谈不下去了，只是之前他对价格就是挺挑剔的。过了一个多月吧，我又发了我们公司新的大板图片给他看，并且说之前我们过，我知道你们只需要2cm的大板，我们这次的大板还是1.8cm，这些产品图片就是发给你参考参考。之后他回复了我说，大板的尺寸他们无法接受1.8cm， 但是可以接受1.8cm的薄板，又发了尺寸过来要求报价。我报完价，他就回了下面这封邮件：（说实话，我们报的价格其实并不算很高）： joe, your prices are not realistic. we, in a single location, carry the largest onyx inventory [slabs, tiles, mosaics, mouldings, sinks, pedestals,..] in americas. we import onyx materials from turkey, pakistan, afganistan, persian gulf and china since 2004, and we pay : $90 - $110 to turkey $90 - $110 to pakistan $100-$120 to persian gulf for a grade white onyx 18"x18" and 24"x24" : without any cracked & fixed tiles, without any dark colour movements and without dark colour spots. white onyx tiles with light colur veins are acceptable, provided that they should be packed in different crates, not together with pure white tiles. dear joe, as you may know, onyx materials from your good country are with large crystals when onyx materials from turkey, persian gulf, pakistan and afganistan, are with almost zero crystals. large crystals drop the quality, so the rates!... because large crystals make the tiles more vulnerable. please check your cost and rates and let me know if you could provide me with better rates for a grade white onyx tiles 现在应该怎么回复他呢？大家帮帮忙吧