Chauvet MOT-2
At a mere online cost of $9 (as of June 2011), this model is perhaps one of the most inexpensive disco ball motors around. It has a 2 RPM motor speed and comes with a mounting hook and a three-prong power cord. It has a weight capacity of 25 pounds.
American DJ M-AC8
While still at the lower end of the price range for disco ball motors, this model boasts more power than the Chauvet MOR-2 motor (above) for only a few more dollars. At $14.99 (as of June 2011), this motor spins at 6 RPM and can accommodate disco balls up to 12 inches in diameter.
Disco Ball EXTRA Duty Motor
This heavy-duty motor is designed to last. Its hard plastic, square casing is constructed to ensure quality and durability. Weighing in at just over 3 pounds, this unit can smoothly power disco balls up to 24 inches. This model is available online for $42.95 (as of June 2011).
American DJ MB DMX-II
Looking for a top-of-the-line motor? Look no further. This model does more than merely rotate a disco ball; it has two three-prong electrical outlets in its casing designed to support pinspot lights, which create a dramatic effect. Its two DMX channels allow you to control three features: You can adjust the motor's speed; turn on/off the pinspots; and change the disco ball's direction. This high-quality unit is available online for $125.95 (as of June 2011).