For large sizes like that, I think you may be able to get good deals on a sort of larger dumb monitor that is used in airports to display flight information, and to a lesser extent rotating decks of static advertisements. They aren't typically sold direct to consumers. I'm not sure whether their pixel response times are good enough for regular entertainment video streams, though.

I haven't done much digging on this, since 40" is plenty for the longest line-of-sight possible in my house.

Yeah, that sounds pretty not-worth it to me.