Seems a lot of money considering you can get a new one for the same or only a little more money. Curiously, what's typically wrong with them? I know some of the earlier flatscreens would lose the backlighting, but were otherwise OK. Still true?
I'm completely ignorant of what goes on in "black boxes" so I can't say. I remember him saying that he has gotten to know the likely problem that each brand and model experiences. Repair parts costs usually run between $75 and $125. Notice that this is all in Canadian dollars and TV sets cost more here.
About ten years ago, before my son started this, I needed a repair on a 46" Panasonic for the second time, that was estimated at $400. I bought a new 65" model for about $2000 and gave the old one to a friend that ran an electronics supply house who repaired it for a bit over $100 and was using it years later in his shop. He too was amazed at how long it kept working.