AC Input for 48 Volt DC Powered Server
My first suggestion, put it back on e-bay :) However, if you feel comfortable using it as a hobby / test server in your home or office, you should be able to get a clean enough 48v power supply from any electronics supply store. Just check the pin out on the server to make sure you're connecting it properly.
Really, though, I'd just put it back on e-bay and chalk it up to an (expensive) lesson learned.
You could always go back to eBay and hunt down a power supply. 48V DC is a telco standard, so there may be more equipment hanging around out there.