LightInTheBox offers this 7" Mini Wireless Bluetooth Keyboard in Black or White for $5.99 with free shipping. That's the lowest price we could find by $4. It features Bluetooth 3.0 and is compatible with Android or iOS devices.
Note: This item ships from China and may take two to five weeks to arrive. Uncheck "Add Shipping Insurance to your order" during checkout to remove the 49-cent fee.