Seriously, I gotta believe you can get a 12 volt solenoid or servo motor cheap. Don't some ventilation systems in cars have servo motors that operate the damper flaps to direct air to various vents on the dash? I think some of these are electric versus vacuum operated. Bet you can get one at a junk yard for about 5 bucks and all you have to do is wire it with a switch. I would drive both ways so it would positively put the choke both on and off.
