I contacted the manufacturer of the server case I got today, and found out that I will be able to get separately the parts that I need from them. That was cause for an instant improvement in my mood today. The only other thing that I would call a "specialty item" (the power adapter cable) I've also found, and just need to order it. That I'll probably do once I can see whether or not the motherboard fits in the case in a usable way. The rest of the parts I can get locally from one of a few places, so those aren't a problem.
Thanks to those that answered the poll from 2 days ago. I actually decided one from the suggestions last night, but was too angry to post about it then. When it comes online, the new server will be excalibur.caerleon.us, and will slowly but surely take over the email and web server duties that my home server currently has.
Still no word from the twats that sold me the server, though. I believe this will be the first blemish on their eBay record :-)