HAHAHA! (Sorry)...but this is the same problem folks are having searching for a nice clean E30. They are out there, but they are declining in numbers every day.
Basically, these cars (E30's and E34's) are old enough that many of them have had 3 or 4 owners, and, for the most part, each owner takes a little less care of the car, until it reaches the point of no return. Many of these cars need so much in the way of maintenance and repairs that it's just not worth doing, even if you get the car for FREE! Seems to me that most of the really nice cars that do change hands never get advertised to the general public, they are sold by word of mouth, to friends, or friends of friends.
The auto trans question is a reasonable one to an enthusiast, but the reason there are so many slushboxes out there is that BMW sold WAYYYYYY more of them when these cars were new (duh). These cars (E34's especially) were pretty high-end luxury cars when sold new, and most americans want to drive autos. Even my old '87 325is had a sticker price of ~$30k !! And that was almost 20 years ago.........
Ask around, talk to people who have cars that you like, and tell them to get in touch with you if they ever decide to sell (you never know......).
Bret.