If you're a beginner I would reccomend something cheap. So if you decide you are no longer interested in juggling, you haven't spent $40 on balls that you will never use. Juggling for the Complete Klutz is supposed to be a great book for beginners, though I don't have it. It also comes with balls.
If you do get more interested in juggling though, i would reccomend buying from www.gballz.com
They are excellent quality. They feel good while juggling, and they are very durable and will last a long time.