I’m wondering if someplace exists that’s the mechanical-engineering equivalent of a Digikey or Mouser - that is, a place to buy motors, cams, linkages, bearings, etc that could be used for small DIY-type projects?
Although a good mail order explosives company is always a useful addition to any DIY experimenter’s list of key contacts. Shame the killjoys at the BATF put the kibosh on that industry.
McMaster-Carr is tough to beat. I don’t find them very expensive. And they are fast - on more than one occasion I have received my order later the same day!
MSC is another good one, somewhat less broad in selection than McMaster and somewhat more aimed at machine shops.
Omega Engineering is known primarily for temperature measurement but they have broadened into various other kinds of measurement and control. If this kind of stuff is ever part of your DIY you should look them over. They rebrand most of their stuff, but they have a very broad range and it is quite easy to use their online catalog and ordering system.
They are a surplus and overstock company, so the inventory will vary, but I’ll bet you will find something that you simply cannot live without on each visit.