i just talked to Joe at software hut about some parts for my a1200. He told me the 4000's he has left are stock, in sealed boxes still and are 1000$ I believe he said, but check in with him if your really interested.
I've only ever seen one of these in person once, in a television studio that looked like they spent quite alot of money on gear.
I'd love to have one someday, but since they are so incredibly rare,I think I might build an a1200 full tower first. If I had the right parts, it would be almost as good I think, and somehow I always prefer custom builds.
Steven