I will have the course syllabi posted on the notes web site by the beginning of next week.
The books are all in the bookstore and available:
Geol 01 -- Earth: Portrait of a Planet by Marshak (2nd)
Geol 20 -- Earth Science by Tarbuck/Lutgens (11th)
Geol 04 -- Natural Disasters by Abbott (6th)
Astr 20 -- Horizons by Seeds (10th)
Hum 10B -- Earth in the Balance by Gore and Beyond Oil by Deffeyes
If you are in one of the lab courses, there are no lab books to purchase. All labs will be posted on the notes site.
You are free to try to save yourself some money by looking for these books on the internets. Sometimes you can get a pretty good deal. If you end up with an older edition, keep in mind that the chapters may not correlate with the syllabus, so it's up to you to figure out what you should be reading.