请帮忙中译英以下这段话，关于商务英语，谢谢。

I am so sorry to tell you that I have to insist on the price I offered before because that is the lowest price we have ever quoted. As is known, the exchange rate between US dollars and RMB is unstable for the value of RMB keep increasing. What's worse, the labor cost for the factories and the operating cost in mainland have increased too.Now, it's already so challengable for us to quote you the original price, not to mention lowering the price. I will be so grateful if you can share the mutual understanging with us.(还请你谅解这句我意译了，译成：如果您能和我们互相理解的话，我会很感激。如果一定要用“请你谅解”的话，可以说：Thank you for your understanding) 1楼的回答很好。简单明了

We are regretted to tell you to maintain the former price, which was a keen price not able to be reduced. As is known to all, the exchange rate between USD and CNY has been constantly unstable and the CNY continues to rise. However the labor costs in our plant are also increasing, as well as the inland operational expenses are going up high. We should say it's quite difficult for us to keep the former price in such cases. Please kindly give us your best understanding for that.

Unfortunately we have to keep the price, previous quotation is already bottom price. As you know, the exchange rate of USD and RMB is not stable, RMB keep appreciation; this year's labor cost and inland operation cost is increased a lot, we do our best to keep the price, thanks for your understanding.