Holy shit dude, how many classes are you taking to have $900 in books? Do you have an option to rent? Maybe I've just been taking the right classes, but over the past two terms (6 classes) I've spent like $300, mostly through the bookstore because I value convenience more than I should.
Congrats on quitting man. I replaced weed, booze and nicotine with tea and coffee about a month ago, but that was after some life re-evaluation. I think it helps not to think about quitting something as starting a new hobby to replace it with. Smoking isn't too time consuming, but I'm sure you could find something to replace it with.