hey come on now, your in law school, before you know it your going to be making the BIG $$$ !!!
That's what I thought. Graduated, licensed, and still temping for peanuts.
Anyway, you may want to try your hand at bigwords.com. The nice thing there is that it compiles searches from several sites, saving you some time. I guess they get a kickback from the vendors (half.com, bn, amazon, etc).
Another option - look in the school library for your books - you'll get the occasional textbook that you can use. But, check as soon as the book list is available - you want to be the first to the library (unless it is on the reference shelf).
Whereever you buy you books, check to see what the campus buyback rules are. I think my college instituted a sticker program since they paid 60% of cover price for buybacks, since some folks were actually making a profit on their books and glutting the schools official textbook pipeline.