Well, do you have a camera ? Because there's a website that holds many many designs for a potentially sub $20 scanner (if you have at least a 6-8 MP camera):
http://www.diybookscanner.org
Also, you could either run it through ScanTailor and produce black and white (not grayscale, grayscale takes up a lot more space), which would be the
fast way, or you could run it through ABBY FineReader and proofread them, style them, etc., and go for
quality instead.