The Pioneer SM-M301 USB Powered Speaker System is on sale at BuyDig.com for $16.99 with coupon code SOUND5 (apply at checkout) and free shipping. Amazon has them for $25, which is about the next cheapest price.
I personally bought these speakers for my laptop a few months ago, and they're really great for the price. Good quality sound, decent bass, and they get REALLY loud for small computer speakers. Definitely worth getting!