LightInTheBox offers the V8 In Battery Flying Squirrels Mini Wireless Keyboard in Black or White for $5.99 with free shipping. That's the lowest price we could find by $4. It's compatible with Linux, Android, Mac, and Windows and requires two AAA batteries (not included).
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.