I had only had two classes that I needed the CD and there was multiple free ways around it. I had a programming class that the book came with the software. The professor let us use his disc or borrow a classmates. One class I had to print labs off of the CD. You could also photocopy them from the book. Also, the library at school had a copy of every text book in use "on reserve" which meant it could not leave the library but you could check it out for two-hour intervals. Sometimes, but not always, the library would have the CD available with the book.
So the long and the short of it, don't worry about the CD. People are always willing to share. Also I don't know if I recommend this or not, but I often bought the next to latest edition of some books. They pretty much contained the same information. Usually it was verbatim with no changes, just a different cover.