Help Find Cost of Building Materials Adj 4 inflation
The RS Means Corporation publishes a series of cost database books, generally with updates every year. Prices of common building materials and systems are included. There is a comprehensive database which covers all divisions of CSI (Construction Specification Institute), which would include everything such as mechanical systems, electrical, structural, finishes etc. You can also purchase specific books that cover only one division such as the electrical book. There are also composite books that cover systems such as interior finishes plus structural components.
None of these books are free. There are competing companies that offer similar products at similarly high prices. I happen to be very familiar with Means, but I have used the Richardson guides, the Army Corps of Engineers books, and the Nuclear Regulatory Commission books as well. There are a few specialty guides not likely to be of much use to you that are free. Since the books generally have annual updates, it would be relatively easy to see how the price of specific assemblies varies by year.