chinese/ebay, aluminum keyboard/half case (protects screen) was $21, and the OTG dongle was a buck or 2...
stuff works flawlessly, and the keyboard even has some hot keys that dovetail nicely with kit kat...
I've got a similar setup now. Using an Anker 15000 battery with a OTG Y-Cable and ElementalX kernel to charge the device while powering mouse or thumbdrive over OTG. Love this Nexus!