You buy them at the local auto parts store and put them either in the car somewhere or on the bookshelf of other auto repair books, of course. I didn't think twice about spending 20% of the purchase cost of a vehicle on the rebuild manual for it back when I drove stuff that needed a lot more work. I drove some cheap cars.

As far as stuff like fridges... you don't need a fridge repairman, just someone who has worked on a variety of things. For a while, while I was doing laptop repair work, I didn't really need manuals for the bulk of the stuff I was taking apart because it was just a laptop. They all came apart in a handful of ways, and as long as you keep close track of where the screws came from and got them back where they went, it wasn't a big deal to get some random laptop apart.

If you can find a YouTube repair of your particular product, and the video is well done, OK, I can see value in that. My experience has been that it's usually a lot of mumbling, terrible light, and weird camera angles that I can't map to anything actually on the product I'm trying to repair, so it's generally not a good use of time vs just going and working on it. Shoving your cell phone kinda sorta in the engine bay, pointing it at some shadows, and "mmfffs the bolt... ffssssh" because it's windy out... eh? Or just a 45 minute "teardown" of a simple product that hasn't had any of the random futzing around and reading the manual out loud edited out.

Maybe we just fix different things.