Hi,
I stumbled across the Cynthia website
http://www.cyndustries.com/
who makes some VERY interesting Modcan Compatible modules incuding a vactrol based Quad Lowpass Gate that appears to be very close to the Buchla module of the same name and can run of =/- 12v. Don;t know if this has been mentioned here before butdefinately worth a visit. Not the run of the mill stuff, quite interesting!