I've had good luck just googling (now duck duck go) the part I needed. There are thousands of tiny specialty suppliers and most provide value beyond the gadget I need.
nailgunsdirect.com had the odd sized nails I needed for a project that were not stocked locally, they also have buyers guides which helped me decide a interesting new nailgun wasn't right for me. toolpartsdirect.com had the switch I needed for my drill, and a wiring diagram so I knew how to hook it up. Racketballworld.com had shoes in my size, and a lot of advice to step up my game. Those are just a few of places I've ordered from - there are many others that that I each which instead of selling everything and making me choose based on reviews only stocks quality products so I cannot go wrong.