No negotiations can occur until after it is listed,the owner supplies all the required short sale documents, and a purchase agreement with a buyer, that the bank deems legit (POF, etc.) is submitted.  

There is not a great supply and they are also higher priced.  

They buy parks that supply water but turn that around over a period of time and make it a tenant cost.

If you are supplying the materials , you hired labors , plain and simple .

The high prices are simply because of supply and demand. 

Last, attend any building supply auctions and pass out flyers.  

Once he has supplied those, ask for the part of his IRS tax return that deals with this property.

My son agreed to do it, as his 'deposit' (landlord bought supplies so it was labor only) They lived there a few years and when move out time came...and place was in great condition...my son wanted his 'deposit' refunded.

what purpose does it serve you to know how much he is charging for framing, plumbing, electric, framing material, electrical supplies?

After that, the Law of Supply and Demand is king.