I'm looking to buy an electric vacuum pump,around 6 cfm,that will pull around 30 inches of mercury.i'm wondering whether a pump from a fridge could handle that,but i'm thinking,not,so probably the type that they use to service air conditioning systems is the way to go.the ones you can pick up with one hand.

Anybody seen these around in the chiang mai area or otherwise,& what sort of cost?

Dairy farm milking machines are vacuum powered and they have vacuum pumps.