Sure, to a certain extent you’re at the mercy of the textbook companies (a.k.a. Fun Killers). But at least you can avoid being gouged too badly by shopping around, plus avoid lines in late January: the Columbia Bookstore and Labyrinth both have course listings online, and although they’re not complete, in all likelihood your calc class will have its syllabus on there. If those prices are still too high to stomach, check out campusI.com, which will compare prices at university bookstores all over the country.
Harness the power of the internet! Because you might as well do something useful while sitting on the couch surfing the net.