Ebay offers Logitech K480 Bluetooth Multi-Device Keyboard - Black for $27.99 free shipping.

Product Description:
The Logitech K480 Bluetooth Multi-Device Keyboard is a unique keyboard that works with your Bluetooth compatible computer, tablet, and smartphone. The Easy-Switch dial lets you switch typing between 3 connected Bluetooth wireless devices on the fly.  You will find a familiar keyboard layout with shortcut keys for Windows, Mac or Chrome computers, as well as Android and iOS mobile devices.
The K480 features an integrated cradle for your phone or tablet at just the right angle for you to read while you type. This fits most phones and tablets up to 10.5 mm 0.4 inches thick and 258 mm 10 inches wide.