I agree with mike in that many shooters that finally go the Dragoon/Walker route decide they are just too big and they part with them. I have seen many like new ones for sale over the pest few years and have also seen multiple forum members tire of them quickly and let them set idle on the shelf in favor more the more common sized versions.
Agreed, my first repro was an SMA 3rd Dragoon. I was thrilled, made a holster, got all the extras, shot it, carried, played with it for about 2 years. Then traded it towards something more useful like a 1911.
But lately I've been looking longingly at a Whitneyville dragoon. Some people never learn.