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.
The reason I shop on Amazon is so I don't have to give shady vendors any of my personal information. I'm willing to pay a few bucks extra for the security that Amazon afford, as long as I'm getting genuine merchandise. Which I can't be guaranteed at Nail Gun Depot either.
You seem to be suggesting amazon is more likely to give you genuine merchandise. This doesn't fit with what I've been seeing lately where people complain about counterfeit merchandise all the time.
I find when going to small sites there are lots of signs that they are not shady: they generate own reviews and advice that is more than marketing. A little poking around will tell a lot. And of course I buy with a credit card so I'm protected against loss in the worst case.
I'm suggesting Amazon can be trusted with my credit card, and implying I would use them over any other merchant as long as I am reasonably sure I am getting something genuine. Prime or Fulfilled By Amazon are pretty good determinations that I'm either getting something legit or I have a very clear path to return the item and get my money back.
I can't say the same thing for a billion other little shops online. If you can't trust that a product on Amazon is legit, how can you trust some no-name site? I can't see how "www.Totally-Legit-Nail-Gun-Depot.info" can be any more deserving of trust than the largest online retailer in the world who has a better-than-world-class return policy.
That's like saying "I've been burned by bad doctors in the past, I'm going to have my brain surgery performed by this guy in an alley". I don't care how many patient referrals Alley Guy has, or that I have life insurance in case he kills me.
But what's the Newegg of other stuff?