OK, so just what are you guys doing with this particular light? Why wouldn't some kind of 120 volt light work. I bet Radio Shack would have some kind of unit that would plug into a 120 volt outlet and transform the voltage to a 12 volt cigarette light plug. You would just have to make sure it is capable of carrying the 3.5 amps. A battery charger would be cheaper though and it would have other uses.
I'm still curious!!!!!