Speaking of UPS's, I was just looking into some myself since I just purchased a new rig. I usually buy a power surge protector but I want something reliable. Any particular brands I should avoid? What about the wattage? What's a good number to go by?
The cyberpower ones seem reasonably reputable, and most tech stores sell them which means you can set a price alert on PC Part Picker (or Camelcamelcamel for Amazon only).
Has a rough calculator. You could use a PSU calculator tool to get an accurate idea of draw (and include monitor or anything plugged into it). I'd just roughly assume off your PSU rating and an extra could be additional buffer. I'd personally have a little more than less in case I can't shut the computer down right away.