They are extremely rare.
Last year, Greg Zanoni (son of Louis Zanoni, one of the engineers envolved in DSM development) sold a few on ebay, it's where I got mine from.
It's the early version with flashing display (1Hz, to conserve battery power, they say). The flashing "feature" is a bit annoying, chances are 50:50 that is't off at the moment you look at the display. Another 50:50 that it reflects something dark so you can't read it either (at least with me wearing mostly black). I like to wear my watches (with great care of course), but I gave it up on this one :(.
I'm only keeping it because it's so beautiful, but if somebody offered me for example a very early Seiko in mint condition (like
LiquidLed's, but preferably with yellow LCD), or a National Semiconductor/Novus calculator watch, I might consider trading it :wink:.
(Edit: image links removed)