Show me those cheap 55" 4k monitors that you speak of. I know Vizio TV that are cheap, but to my knowledge no 'monitors' exist in that size or price range.

You are right, good monitors are more expensive than TVs. Especially monitors that can do 23.976Hz and 24Hz refresh without resampling.

But why do you need a 4k monitor, to use as a TV, since all current material is 1080p? Better buy 4k when there is a need for 4k, then the price will be lower.