Dell Home, via its Member Purchase Program, offers the ZAGG Pocket Bluetooth Keyboard in Black, model no. APLPOC-BK0, for $49.99 with free shipping. That's the lowest total price we could find by $10, outside of the mention below. This folding keyboard features a USB charging cable, LED battery indicator, and magnet closure.
A close price: Amazon charges $51.49 with free shipping. Note that Dell's Member Purchase Program is available to select groups, including students, government employees, military (active and retired), credit union members, and health care workers.