The Patridge sights fitted with gold, not brass, or ivory flat bead from 1925 to 1942, was designed by Charlie Call. I do not believe that either the Call or Sheard sights were all that scarce. I have a few of both. Starting in 1937 until WWII, there was also a McGivern exposed gold bead front sight. I would tend to think that sight would be pretty scarce since it was only available for a few years.
According to Bob Neals study on S&W sights, the Sheard sight was gold and ran from 1931 to 1942. I also have those Sheard front sights on a couple guns from the 1910s. Of course, those front sights could have been changed out at any time by the owners. They would have been on hardware store shelves by the 1920s & 1930s or available mail order. There were probably over a dozen front sight blades available on guns before WWII and most target revolvers ended up going to hardware stores, so standard sights would have probably been put on those guns.
I think that the majority of front sights were either thin front sights or plain Patridge ones. Plain Patridge ran from 1900 t0 1942. Thin blades ran in the same era as the Patridge. The plain thin sight had rounded corners, allowing it to go into and come out of a holster easily, but the Call, Patridge, and Sheard might not have been the best choice for a holster gun.