In September of last year, I bought a Wacom wireless tablet for a test of creating a cheap brightboard (whiteboard). The total cost was about $215 and it did work. However, now I would suggest buying an iPad or iPhone and using an app like the Mobile Air Mouse ( http://www.mobilemouse.com/ ) for the same purpose. Mobile Air Mouse connects via WIFI and allows for keyboard entry and media control (if you purchase the Pro version).
Build Your Own Brightboard