There are several sources for Nomex long underwear out there. Race car drivers wear the stuff religiously, so searching around those kinds of sites will find good stuff. I have Nomex long underwear that I bought from Flight Suits, ltd probably ten years ago. Stuff lasts forever, and it actually is warm and wicks pretty well.
A number of years ago, I asked the equipment supply guys in the AF fighter squadrons in Alaska if their pilots actually wore Nomex underwear in flight in the winter, or poly pro.... Their answer was that most of the pilots were wearing poly pro. The logic there was that if you CRASHED in a fighter, you probably don't have to worry about fire. But, if you eject and it's winter...... The equipment guys couldn't argue that point, and went along with it.
Most of us don't have ejection seats, though.
Lots of good suppliers of nomex out there in any case.
MTV


Please lets be safe out there.