dont forget about the motion computing le 1600 and 1700 tablet pcs............they are awesome for drawing i got one a few months back and like wow very very responsive and no lag unles you use photoshop to draw (or use a thousand layers) but its good i use sketchbook and sai. Also its the cheapest on the market i got my for $75 used just for a small crack on the screen and the go from there to $185. i think the most expensive is like $400 new but why buy new ones when the used ones are very decent. plus its an excellent alternative to the wacom cintiq 12x because its a 12 inch screen as well almost $800 cheaper
A Cintiq is a really nice thing, but very expensive. And digital drawing is a bit different than traditional. And some Persons get tired of digital drawing cause its to complicated for them.
So what about a Wacom Tablet first? (Like the Bamboo Fun)
I've done it that way: I've bought an Convertible PC (old one) at ebay, the funny thing, the Screen was made by Wacom. (its the Lifebook T5010, i've bought it for 200 Euro) Pimped it a bit and learned how to draw on that screen (its the same as on a Cintiq). The quality is very good, just the smaller screen is the difference.
Now im going to save money for the Cintiq, cause, i haven't lost interest in digital drawing and will go on making these kind of art.
I hope i've helped you a bit and looking forward for your decision