I'm a cheap nerd, so I printed myself an enormous wall decoration last August 2006: it's Pi, in a textual fractal. (This is it to two levels, and the one in my room is to five.) 3'x5', $10 from Kinko's. Nice conversation piece.
I've been printing more things recently, I've been thinking about combining text and images, and an author of two books on classical themes bemoaned the expensiveness of art in an email today. (Illustrating an book on Aesop's Fables, specifically.)
Most art schools have job boards; the artists can be of varying qualities, but sketches in pen are quick to do, and hard to do badly. (Lots of approximate lines.) Twenty seconds a sketch, which is a not-too-fast speed, scan one as you're doing the next one, and you've got a hundred in an hour.
Has anyone used Flickr for (cc)by-sa images? I wonder if that's cheaper.