I just bought a new 50" ONN 4k Roku TV from Walmart for $218 and it is a shockingly good monitor. This replaces a JVC 49" 4k TV that I had to adjust many settings, for it to work just so-so as a monitor, and died a premature death. This ONN TV has a very easy setup, that when complete does not require any setting changes to get a perfect setup for use with a computer (the setup asks you what you will connect to each of the three HDMI inputs). I also have a 39" and 42" Seiki so moving up to a 50" was no problem. They both work great as a monitor.
Turveyd, I know you know this but for others, a 50" 4K monitor is like four 24" monitors. The advantage over four monitors is cost. Any APU in recent years can power a 4K monitor, so no need for a graphics card let alone an expensive one. The advantage of four monitors is you can angle them to face you better. I am a programmer so screen realestate is king.