Maybe I have been hanging around rarified circles as ret said. When I first moved to Newcastle (Blackalls park)there was a guy around the corner with a FC that had the wilsonia gauge, I spent alot of time growing up at my Nans house were my uncle lived, he also always had wilsonia gauges in his cars, just before I moved down from Newcastle (Belmont)there was another guy around the corner who not only had them in his cars, but always had some for sale, Sometimes Craig Wilson comes around here and he also has one, what have you got Alex?
There may be less chance out in the real world I would say that quite a large number of those cars are owned by non club members are also old holden enthusiasts.
we arent exactly talking nissan pintaras here and not many people buy a FE or FC without a good interest in them, even if a non enthusiast did chances are the previous owner was a enthusiast.
I usually see at least one of these units at a swap meet and I think if I wrecked out a car that had a wilsonia gauge I would clean it up and sell it seperated from the rest of the instrument cluster, I would also only be selling it if I had one in my car. (wich I plan to get once I need to put a boost gauge in my triple guage cluster under the radio)
I dont really think it would be one in a thousand unless you want to include remains hanging out of creeks.
Rare spares should have advertised on ebay, it really shits me that they went that cheap and I missed out as it looks like its going to be hard now getting one for less than $200 2nd hand.