I don't have any hard-and-fast figures but I can say that I've never seen one and do keep a wide eye open for 327s.
The SP101 is a lot more common, but still not easy to find. I've kicked myself frequently over selling mine.
I can guarantee you that my Single 7 won't be going away any time soon.
I'm not a Ruger guy but keep an eye open for these guns since they have been the only company that has really offered any sort of variety of 327. The only think I recall from S&W was a J-frame. The ballistics(in particular the high velocity and flat trajectory) make it a very attractive long-distance and varmint cartridge. It's a shame it never caught on, as it's a superb cartridge.
I have a "thing" for hot 32 caliber handguns. The 32-20 of course is the old standby in this area, but the 327 Mag beats it in almost every way. The only area where the old 32-20 shows its superiority is when it's shot out of a strong rifle action(i.e. a Winchester 92) and the greater case volume allows you shove in a great volume of slow powder.