Scanner Suggestions (for textbooks)

All right. A lot of my textbooks aren’t available in a PDF format, which really pisses me off. I refuse to lug textbooks, notebooks, and binders because my tablet PC should be the only thing in my bag.

What makes a good scanner? I want something inexpensive but also produces high quality scans. Are there scanners that will make the process easier/faster? Perhaps there is a type of scanner that is placed on the book instead of the opposite.

Also, if anyone out there has actually done this, how long did it take? I can’t imagine scanning thousands of pages within only a day.