Analogue Solutions Red Square http://www.analoguesolutions.com/ or any modular system http://www.synthesizers.com/ ($120 a month for 12 months gets you a working system with room to expand. -- http://www.synthesizers.com/system-entry1.html) http://www.cyndustries.com/ http://www.modcan.com/ http://w...

Also try Starving Musician locations in Santa Clara (not too long ago they had an Obi 4voice) and Santa Cruz.

Guitar Showcase Consignment Shop in Campbell (occaisonally some rare stuff like Memorymoogs and a Matrix12)

otherwise scour craigslist