Supplier: McMaster-Carr

McMaster-Carr (mcmaster.com) is one of those places you turn to when all other sources have failed to turn up the required parts. Odds are McMaster will have it if you need it. Chances are they will have it at a decent price and be able to ship it quickly too. I have had orders shipped the same day I ordered them which results in next day delivery quite often.

They have a large selection of materials, tools, fasteners, safety equipment, and just about everything else. Check out their site and browse the catalog to get a glimpse at what they carry. And, if you ever come across one of their print catalogs, grab it. They are quite large and comprehensive and highly useful for looking up various parts.