Yeah, I just don't get enough money for English class books. The only time I sold back I got $12 for at least 7 books. For that amount I'd rather keep the books. But I understand why people do sell them back -- and it's helpful. I buy used if I can (and if I can find an unmarked copy in decent condition).
Hey, I had to read Midnight's Children, too! Most of the books I read and liked came from one class--Contemporary British Literature and Culture. We read White Teeth and London Fields. I also got to read some Joan Didion for one class (which I liked enough to go out and buy her books) and The Good Soldier, which wasn't a fabulous book, but it introduced me to the concept of unreliable narration, a fun topic if ever there was.
Also: I donate English-major-related books to my local library if I don't want them. It's a good cause and it keeps my room free of clutter.