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.
The Amazon Echo Show is an Alexa speaker with a screen, which opens up the ways you can interact with the digital assistant. However the Echo Show's strength lies in not trying to do much more, remaining simple to use while adding video chat, which comes handy for a mere $50 extra over the standard Echo's asking price.