I havnt had a chance to hear the highly regarded Swan m200s. Under $50 shipped though, these are probably your best bet :

http://www.meci.com/advanced_search_...0-0272&x=0&y=0

$17.95 and shipping starts at $18.

Had one of these few years ago, and they rival (except for the obvious lack of bass) my midiland S2 4100s which arent too bad in their own light. I guess you could throw in a powered sub in the mix if you must have some bass, though I doubt thats needed as this is for under $50 minimalist setup.

One caveat : while they dont show up as out of stock, I havnt tried ordering a set myself...