This is the only site for Simplex. This is a limited hobby for sure, as most of the older guys that owned these as youngsters are dying off. Sort of like the cars from the 1920's to late 1950's are loosing there luster,and value, as that generation dies off.
For a reference, I have bought 4 automatics in the last 5 years, none running but mostly complete. I have paid from $700-1400 for these non running bikes.
I think you need to put a value on it, and go from there. If not, eBay is always an option.
BTW, that is the Wico magneto they used from 1940 until they changed to the Phelon sometime in 1955-56. The breaker plate for that magneto needs to be replaced.