1. General: A usefully accurate way to find out current material prices is to go to the Home Depot website and search for the item or material you're interested in. If you're using this information to verify roofing estimates, remember that contractors usually get volume discounts on the visible retail price at Home Depot, Lowe's, or any place like that.
2. General: Another good source of current material prices is the GSA Advantage website. Quoting from the GSA (General Services Administration) website: "GSA Advantage!® is the online shopping and ordering system that provides access to thousands of contractors and millions of supplies (products) and services. Anyone may browse on GSA Advantage!® to view and compare the variety of products and services offered."
This is the "roofing products" search results page. You can search for whatever product you're interested in and get "pre-competed" price results.
3. General: "Construction Data - Producer Prices and Employment Costs" is over on the website of the Associated General Contractors of America (AGC). "Each month, AGC puts out tables and an explanation showing historical and recent changes in producer price indexes and employment cost indexes for construction materials, building types and subcontractor segments."
4. General: Here's an interesting link: the University of Wisconsin-Madison Purchasing Services Division of Business Services publishes their most recent contract for roofing materials and installation services with one of the largest commercial roofing companies in the US with a breakdown by unit price of over 70 items related to the work. Gives you a really good idea of what this stuff actually costs. At least in Wisconsin.
5. General: Best Materials provides prices for a huge assortment of roofing products.
6. General: BuildDirect provides prices for an assortment of roofing products.
7. General: Grainger Industrial Supply provides current prices for a few construction materials.
8. Copper Prices: Basic Copper gives prices for copper nails and copper sheets and rolls.
9. Fastener Prices: FastenerUSA supplies a variety of construction fasteners and lists their prices.
12. Roof Drain Prices: Josam roof drains* on Amazon.
13. Used Materials Prices: repurposedMATERIALS has prices for used construction materials and equipment. This is kind of a fun site to look through.
14. Ventilation Products Prices: Active Ventilation Products provides prices for a variety of prefabricated items.