http://www.analoguesystems.co.uk/controllers.htmScroll down; they've got a version of the Sorcerer called the Demon that is a
stand-alone CV keyboard with built-in joystick. Not cheap, but looks decent
(although it has those annoying 1/8" jacks).
Look at the bottom of the page too... I think the French Connection is based
on the Ondes Martenot.
Question is... do you spend twice as much and just wait for the Big Briar
Voyager?
Ivan