i can tell you right now what you are going to hear from people, since this is a common topic...
i like my altec lansing acs-48 speakers very much and they are a bit under $100
a good number of people like the altec lansing atp-3 speakers and they are closer to $50
yet another group of people have high opinions of the labtec pulse-424 as a great bank for the buck at $45 or less
others speak highly of boston acoustic speakers (i'm not familiar with them but there's a 3 piece setup in your price range) or they might tell you to spend a bit more and get the ba-4800 (i think) 5 piece and stack the satelites on top of each other (making 1+1 on the right and 1+1 on the left, taking up the same space as a 3 piece setup)
there might be a few other opinions here and there but i think this sums it up...focus on those (since most people have) and you might want to try a search for speaker topics in this forum
edit: darn, noriaki beat me, but he did mention a few of the speakers i mentioned, and i left out the klipsh because of the price