Dr. M,
In the IHMSA world of shooting, all production equipment (including grips) must be commercially available in quantity to be considered production. I believe that they need to be made from a pattern and must be approved by the appropriate IHMSA committee. There are some rules about having a catalog, etc. to be 'approved' for production As for unlimited, that's another story, but basically anything goes.
There is already one person in Texas (IshmaelCustom) that had his grips approved for production and they are quite popular.
As for demand, I personally have all I need, and about 6 extra sets that may soon hit the classified board.
Bill