Rockwell Tools via eBay offers its open-box Rockwell Shop Series Sonictool Oscillating Kit with Universal Fit, model no. SS5120, for $37.99 with free shipping. That's the lowest total price we could find for a new unit by $21. It features a 2.3-amp motor, variable speed control, and adapts to other brands accessories.
Note that this item is new but has been re-boxed in a plain brown box.