More than the cost of a new TV. They are built in such a way that screen replacement is nearly impossible. The panel and the controller board are different for virtually every model of tv, so no one really makes replacement screens. You would have to find the original manufacturer of that specific screen, and hope they still were producing them, which they probably aren't since they are making new models.
Your only hope is to find a used one that has a good screen, but is broken in some other way, and swap yourself. This is a hassle, and there is no guarantee it will work in your favor (as lots of things can go wrong). I tried this route myself, and I would not do it again.