I just want to subtly point out that your question cannot be answered and that the whole thing (whatever your intention behind the question is?) can seriously backfire on you.
I see this as an exchange of experience. Of course you can do that. Stop always answering everything in a smart-annoying way. For hard-to-understand people like you, I will explain the intention of my question once again. I see this whole thing as an exchange of experience and want to know how much other builders have paid for their roof. Is that so hard to understand?