The bottom line is that it is a great place to buy some hard to find products or easy to find products for a good price. Almost anything you can think of is on there.
The flush valve on the toilet in the guest bathroom broke. It is not a standard flush vale and none of the local hardware or big box stores sell them. It is the American Standard brand that fits the toilet.
American Standard 3174.002-0070A Champion 4 Replacement Flush Valve - - Amazon.com
Back when I put in the toilets I could see I would never be able to find one easily so I went to the local professional plumbing supply store and stood at the counter next to the real plumbers. They looked at me and instantly knew I was a homeowner and self fix it guy and charged me the bend over homeowner price for a flush valve. It was over 30 bucks. I had little option of finding one anywhere else.
The Amazon price is $19 and that is 10 years after the local store charged me 30 bucks. I did not have to drive to the store. It will show up in a couple of days.
Next I need to go buy a used uniform from a local Cintas. One with a shirt with Bob's Auto repair and one with Jim's Plumbing. Maybe one with Sam's electrical on it. When I go to the parts counter they will think I am one of them.