Festool has repackaged their new 12+3 and 15+3 lithium-ion powered cordless drills making them a bit easier to afford. The Festool T12+3 sells for $400. The Festool T15+3 sells for $450.
The trick to picking up a heavy sheet with a Gorilla Gripper is to get your hand under the Gorilla handle and fold your arm under the load while you bend your knees, and then straighten your legs to lift the material. Your hand ends up at your shoulder and the heavy sheet hangs comfortably by your side so you can walk with it.