It seems that I read when the Dynaudio Evidence's came out that Dynaudio "considered them to be a production product" (I guess some manufacturers don't?) and were projecting sales of a couple (few) dozen pairs a year. I don't remember the model numbers exactly, but I remember reading a review of the Levinson monoblocks (33H?) that retail for around $18K that they were developed in response to the "overwhelming" demand for for their flagship monoblocks (33?) that went for over $30K, but they were limited to being able to produce only about 6 pair per month, whereas the newer (cheaper) model they'd be able to produce more of.
Taking into consideration the vagueness of these memories, my guess is that "successful" state-of-the-art products sell between 20 and 100 "units" per year. -Kirk