Used to be so many stores that sold parts for self repair. Most of them have disappeared (at least around me), and the few that remain are either a ridiculous drive away, or ridiculously expensive. Like, sure, I could drive 3 hours to your store, buy the part I need for 70 bucks, and drive 3 hours back home.
Or I can go online and order the part and have it in a day or two for less than quarter of the price.