Pete's given us another great one! This thing looks cool - I've already started ordering parts. I had a bit of trouble finding the power supply, but this link should help you guys:
Cisco 34-1977-03 48V 0.38A PSA18U Power Supply NEW - eBay (item 360035479615 end time May-20-08 14:46:30 PDT)
The guy is down to 92 from 100 in the last hour, so they may be going fast!
I'm guessing the ingenious method of loading the MOSFETs with the tube heaters means they're already biased at 150ma. Sounds like a neat trick all the way around.