I had toyed with the idea of using a TV as a monitor on a couple of different occasions in the past decade with no success, but with the advent of affordable 4K sets using a TV as a desktop monitor is finally feasible. Here's my experience during the past few months.
Amazon's Deal of the Day is a certified refurbished Samsung U28E590D 28" 4K monitor. We picked this monitor as a great buy back in 2015 as an affordable 4K option, but $270 is ridiculously low even for a refurbished unit. Of course, you're not getting state-of-the-art specs, but user reviews back it as a solid 4K offering for desktop work (not so much for gaming, in spite of FreeSync support). If you're coming from an old monitor, this will do great as a cheap upgrade, however note this is an affordable model with no height or swivel adjustments.