Kent Displays, right out of my home state of Ohio, is a pressure sensitive display that allows you to right, sketch, doodle, etc. It is selling for $29, though it seems to be unavailable at Amazon right now.
The only catch is that a tiny battery “wipes” the screen to erase it. But, it can last 50k cycles. Er, that will last a while. Most people who have tried it really like it. It would be really cool if you could wireless send the drawings, notes somewhere. Of course, that would crank up the price, but may be worth just having bluetooth connectivity with some software on a computer. Just a thought.