Don't forget your family's lungs. I don't really order the right sorts of things, but my wife often orders things that arrive smelling like they were dipped in benzene before leaving the factory.
Kind of a good metaphor for how toxic Amazon as a whole is, actually.
Yeah, it depends on what you're looking for. McMaster is great for high quality serious Machine Shop level stuff, not so much for household oddities.
Recently I needed some vinyl siding hooks[0], a really oddball size drawer slide, and replacement window springs. I ended up getting all of them on Amazon - even tracking back the manufacturers they seemed to exclusively sell on Amazon.
I'm pretty much down to a few books, video games, and obscure fasteners/hardware/tools (which annoyingly they're just about the only good source for).