[sl.whiteside]

How about this?
Put a very small air compresser inside a vac tank and run it? Put the pressure side to the outside of the tank.
WALAH....a vac pump.

A great idea! Only worry would be that these pumps rely on air for cooling the motor and the compression cylinder. You might want to add some extra heat sinking to maintain the reliability of the pump. I would also put an inline filter on the output of the tank to keep compressor grit out of the line.