I'm taking a look at this
Photoshop Touch app thing they announced earlier this month for the Android. It looked like it might do the trick for letting me sketch something on the tablet, then export it to PDF and touch it up on a desktop. Android tablets are like 200-500 tops, which would be nice.
Unfortunately, looks like you can only export images to THE ADOBE CREATIVE CLOUD™ and you need to pay a monthly fee for that (which will ratchet up the cost of doing such a thing for a year or so well into Might As Well Get The EP121 territory). Plus, well, yes, the touch screen on the Android is not really built for that. It's not pressure-sensitive or generally thin and responsive enough to be sketching on.
It feels like there should be some older and cheaper Wacomish thing that can just run Photoshop without being a piece of shit, but I guess tablets are only now really starting to get interesting.