I bid on a pallet of used APC UPS equipment in a semi-local online live auction. I figured for my $50 I could at least salvage a transformer or two and some parts. I bought several smaller units (420va, 600va) the same way before for $20 and just replaced the batteries. Well, turns out I got a SURT7500XLT UPS, two SURT192XLBP Battery Packs and a SURT005 Step-Down Transformer all in working order. With bidder's premium and sales tax, it came to $59.54. New, this setup retailed for over $7,000.
Apparently, a data center bought all new equipment and this equipment was too small for them after expanding. It is "used" but how much does a UPS system GET used? The batteries show about 75% charge so it's been sitting but what the heck. There was only one other bid so I'm thinking no one knew what it was. This is a 6000W/7500VA Uninterruptible Power Supply. This thing could support most if not all of the 120v circuits in my whole house.