The simplest thing to do would be to attach a die grinder to the shaft of the blender, and a regulator to the handle of of the grinder, so you would be able to adjust the speed of the blender.

I have thought about the gas ones, but they do seem to be a bit of PITA to set-up, use, etc.  I gave a 12vlt(high end model) to a buddy and his wife for Xmas a few years back, but they never remember to bring it, so I don't even know if/how well it works.