Thank you all for the helpful responses. As is often the case I find myself amazed at what CAN'T be purchased despite a clear need.
My other recent experience with this was for something much more basic, but also unobtainable and (for me) very important: I have tight clearances near my power conditioner, so I was looking for a simple right angle adapter (NEMA male to NEMA female) to change the angle at which plugs would enter the power conditioner. Couldn't find them anywhere! Even at electrical supply houses. Sure I could find right angle power cords with cheap wires, but I just wanted the shortest possible route to do this.
I guess it's the old rules of supply and demand, but this hobby sure can be frustrating -- if I consistently have issues like this come up and my set-up is not particularly unusual, my guess is that a large portion of us have issues like this with some regularity. Maybe I'll post a new thread...
Thanks again.
--dan