As a grad student and a parent of a college freshman, we check out all sources for textbooks from used bookstores, online textbook rental sites, Google books, and college book swap sites because the college bookstores are overpriced. If you have a favorite textbook site or source, please share it as a comment.
Gupton, S. L. (2003) The instructional leadership toolbox: A handbook for improving practice. Thousand Oaks, CA: Corwin Press. ISBN: 9780761978268
Ornstein, A., Behar-Horenstein, L., & Pajak, E. F. (2007) Contemporary issues in curriculum. New York: Pearson Education. ISBN: 0205489257
Wiles, J. W., & Bondi, J. C. (2007) Curriculum development: A guide to practice. Upper Saddle River, NJ: Prentice Hall. ISBN: 9780131716889