EC Technology via Amazon offers the EC Technology Foldable Ultra-Slim Bluetooth Keyboard in Black for $36.99. Coupon code "EDK3AXVW" cuts it to $23.99. With free shipping, that's $46 off list and the lowest total price we could find. It works with most Bluetooth-supported devices and measures approximately 10" x 3.5" when open. It features a purported 60 hours of usage time per charge.