Best quality for your money is going to come from a good set of stereo speakers rather than a 2.1 system.
http://audioengineusa.com/Store/Powered-Speaker-Systems/A2B-Powered-Desktop-Speakers
The 2.1 systems will give you more deep bass, but often boomy and not balanced with the rest of the audio.
Audio Engine are not a cheap brand.
If you hunt around you may be able to find good quality stereo speakers a little cheaper.
Alternatively, if you look through their range and read some reviews it might inspire you to spend a little extra and get something exceptional.
If you happen to be in Australia, Swan Speakers make some good stuff:
http://www.swanspeakers.com.au/products_multimedia.html
Creative also aren't too bad, but not in the same league as Audio Engine.