Altec Lansing VS4121 2.1 Computer Speaker System (Refurbished) $38 Shipped
Midnightbox has the Refurbished Altec Lansing VS4121 2.1 Computer Speaker System for $33 plus $5 shipping. These have great reviews and seem to be one of the best sub $100 speaker systems.
Features:
Serious Power
Deep Bass subwoofer
Crisp high end specially engineered micro drivers
Exceptional Sound Dispersion from down-firing midrange driver