Check the Dannysound listings, also...they've got a module that's just the Buchla 259's waveshaping section. Feedback themselves also have something similar.
Amazing, really...Buchla used to be prohibitively expensive, and now we've got loads of Buchla-type stuff, and even actual Buchla (via Tiptop, or via several other companies that do Buchla clones) stuff in Eurorack now.