Hey there Dave,
Looks as if your WD3 was manufactured by Mercury Kiekhaefer in 1946. There were several other manufacturers but they came after Mercury. Value is a very subjective issue depending on a number of things. Does it run, is the paint good, are all the parts there, etc. It all depends on condition. It would be good if you posted some pictures and info.
I also have a WD-3. It was the first Wizard model from Mercury to come out in 1946 after WWII. They are pretty much identical to a Mercury KD3 with the exception of paint and decals.
They are fun little motors and eye catchers at the boat landing.