Client add shipping cost

[ngruy]

Hello,
Is there a way that i can give the option to the client to add a shipping price in her order?.
I ship the products free for some areas and (majority) but some customer need to ship products to some area taht i need to add some extra fee to it. The shipping fee depends on the product, and zone of shipping.
The client send us an email requesting for the shipping fee.
So i need to know if it´s possible to the customer to add this shipping fee manually in order process (or maybe they can add a special product that they can be edited), so they can make a check out with the exact price they will be debited.

Hope someone can understund what is my point (sorry for my bad english).

Thanks in advance!