I have UPSs on all my computers and home theater equipment
At home, I use a 6 year old APC's Back-UPS ES 350 for my old (now mother's) huge Dell dinosaur. However, it can only power the computer for 3 minutes from it's original 20. I'm not going to get another one as I want that computer to die.
I use an 10+ year old APC smart ups 1400
Sort of would recommend buying a reconditioned 1400 or 1500 for big machines and a reconditioned smaller one if you don't need something as big.
A lot of people buy new when the batteries die, so there are some decent ones out there.