I'd recomment these speakers for ~$30. (free shipping)
http://www.2buystore.com/shopdisplaydetail.asp?id=595048
They are basically the 2.1 version of the Cambridge Surround system. That is to say, you only get two satellites (plus subwoofer) instead of four satellites. I have the 4.1 version, and it is quite nice for music and gaming.
I recently learned the trick to the subwoofer: it sounds much nicer if you point it towards a wall, because the wall vibrates and becomes part of the woofer, so to speak. It's better to point the subwoofer at a wall than to point it towards your ear. Now it has quite a nice bass sound.