I'd like to recommend something out of the ordinary but to be honest you are best going with a Wacom. Wacom Products
the lower end models are still better quality than most others. if you are in the states you'll get them for an average of $100 for the 4x6.
the price goes up from there for more surface area and the higher end intuos and features you probably won't ever use.
Then there is the mecca of tablet tech at the moment, The Cintiq ($2500.00+) The pen alone costs $70.