Yes, I think it can be worth it to buy some knitting books. I just bought the Knitting Answer Book http://www.amazon.com/Knitting-Answe...798540&sr=8-28
which gives me great references on things I didn't know as well as basics. I love to have pattern books (or magazines) around, too. One thing I would recommend, though, is that you try to buy more classic designs, or things which will work well over time. Some good basic hats, mittens, scarf, or design-your-own sweater type books are good references, though.