Mine would be (now this is not a single item, but... was all connected)

about a year ago I ripped apart a 4 cabinet data closet that I paid $200 for the right to do. The property owner needed it gone so he could lease the office out again and I wound up with about 10x what I was hoping for. Scrapped quite a bit of it and resold quite a bit of it. There were a couple really valuable Cisco servers and a monster APC UPS left in there. Cha-Ching.