Order is not so easy

The big order of 93Km fence is a litte far from me,it's out of our control.

Client request new quotation,and change many size with better material,in this way,the new price will be double higher than the previous one.I don't know so higher request,mesh fence diameter is 3.76mm,with line post 60mm,the best we can do is USD13.4/M,but their target price is only USD8.9/M.13.4-8.9=4.5USD,see this big difference.This means if we accept this price,how much loss we will get.But if say no,order will leave us.What can I do?How can I do to change this embassring situation?
UAE mes fence client tell me something?I am lost in this totally!