In this web world, not all wisdom is on the web. Over the course of the semester, you should spend that money wisely. For starters, I recommend a subscription to PC Magazine or Dr. Dobb's Journal . Plan to spend an hour or more browsing. If you find a book that doesn't make you puke, buy it.
Different books speak to different people with different needs.
If you find a book you wish you had read yesterday because it answers the questions with which you are struggling, it is a good choice. If you find a book that you could have written better or one that is over your head, simply put it back on the shelf. I also may appoint 1-3 students as volunteer assistants. There will be no pay no extra credit, and no release from the work of the class. You WILL probably get glowing reference letters for a job, if you ever need them.