I am a member of that Yahoo Group, but it is a little on the quiet side, and of course it is not one of those I mentioned.
The Grepstad site is well known to me and is indeed a good source of information for camera builders; after all his design is probably the most influential among modern hobbyist camera builders, thanks to his book. However, several of the links of his page seem to be dead; I should have downloaded Daniel Rhoades' camera design drawings before his site went offline... *sighs*
So the search continues: I am still searching for brass rack-and-pinion gears, preferably available locally. among other necessary parts.