As Camicao points out, textbook prices are outrageous. On one level, that's understandable: textbooks often cost more to produce, and have a much smaller potential audience, than most general books. Publishing isn't really a high-profit business to begin with, either. However, it's still insane to have to spend $250-$350 each semester, as I did, just on books. Depending on your classes and where you go to school, you can spend a lot more than that, most of which you'll never recover, even if you're lucky to be eligible for book buyback (which hardly gives you anything).
But, as you all know, I'm a textbook fetishist. There's just something about them (the paper, the covers) that I find intoxicating. And the alernatives are simply unattractive. E-books and professor-provided .pdf files (Camicao's suggestion) just aren't practical, in my view. You either have to sit and read them off a computer screen (which is impossible; your eyes would burn up) or print the whole think out. Now, I don't know about you, but I wouldn't use MY ink to run out a couple thousand pages, which is what it would add up to if a semester's worth of books were all online. And using school labs would be very problematic. One, I'm sure the other kids trying to print things out (not to mention the poor printers themselves!) wouldn't appreciate waiting for my 250 pages to spit out. Two, I'm sure schools would soon crack down due to the cost of paper, ink, and maintenance.
So, basically, at this moment, I see no option but to buy the textbooks.