Regard's
Arlene
For all we know he might be located in the arctic. IMO a few hours of downtime would not justify the investment cost for a brand new UPS. I get frequent short blackouts, too. I hooked up a used heavy machinery battery to my 600VA APC. It takes forever to fully charge but I have a very long runtime for my computer, DSL router and sound system. If I go the DC-to-DC route, it almost doubles the runtime.
Big ass heavy batteries + big ass battery charger + big ass DC-DC regulators might be OPs best bet. Being able to find cheap batteries and having the electrical knowledge to hook them up properly is the key here, I think.