Sure the "DC UPS" are basically "simple dumb batteries", but the sort of loads that you'd probably run off them and the expected runtime of each tends to be quite different.
Guessing the average AC UPS that someone might back a desktop with might last 5 minutes (or in a data centre long enough for the generators to kick in). A "DC UPS" running a router or a raspberry pi likely has a runtime measured in hours. Still would be nice to have monitoring info available, but more time for human intervention to shut down if need be.
"you might as well roll your own for less cost and much more runtime..."
Depends on how much gear you want to power. If you just want to keep a raspberry pi online a few hours I doubt you'd save much money (if any) rolling your own. Could be fun as a project though.
Guessing the average AC UPS that someone might back a desktop with might last 5 minutes (or in a data centre long enough for the generators to kick in). A "DC UPS" running a router or a raspberry pi likely has a runtime measured in hours. Still would be nice to have monitoring info available, but more time for human intervention to shut down if need be.
"you might as well roll your own for less cost and much more runtime..."
Depends on how much gear you want to power. If you just want to keep a raspberry pi online a few hours I doubt you'd save much money (if any) rolling your own. Could be fun as a project though.