Your TV repair guy is about right. Any defect in the display (not the electronics) will cost more to fix than a new set. An electronics failure can be costly since they won't fix the board, but swap it out.

The longer you wait, the less you will pay for this new technology. Also you want the longest FACTORY warranty you can get. 2 years gets you past the usual failures.

It will take years for all this to settle out, but spare LCDs and such are unlikely to be stocked by the repair companies for the simple reason that such will fit only a small number of displays and the cost...