The ASUS Chromebit CS10 was one of the first desktop Chrome OS machines, as it was released in 2015. It squeezes a Rockchip RK3288C processor and a 2GB of RAM into a package the size of a Chromecast, and now you can get a refurbished unit for just $59.99.
The full specifications include a quad-core Rockchip RK3288C processor (clocked at 1.8GHz), 2GB of RAM, 16GB of storage, a single USB 2.0 port, and Bluetooth 4.0. It connects to any HDMI-compatible TV or monitor, and works exactly like a Chromebook. We reviewed the Chromebit in 2016, and it was already a great value at the original price of $85. The 2GB RAM is a bit limiting, but the Chromebit is still a good option for light productivity or media consumption.
The Chromebit CS10 is guaranteed to get Chrome OS updates until November 2020 (at the earliest), but you cannot run Android apps on it. It will probably never get support for Linux apps, but if you feel so inclined, it's possible to install Arch Linux.
You can buy the Chromebit from Newegg at the link below. If you plan to use the Chromebit with a TV, you might want to buy a wireless keyboard/touchpad to go with it. Microsoft's All-In-One media Keyboard and Logitech's K400 Plus are great options, though their receivers will take up the single USB 2.0 port.