Amazon offers the Yamaha 5.1-Channel Home Theater Speaker System
, model no. NS-SP1800BL, for $97
with free shipping
. (Fry's Electronics
charges the same.) That's the lowest total price we could find by $43, although we saw it for $9 less in June. It features a frequency response of 28Hz to 50kHz, 100-watt 8" powered subwoofer, four 2-way satellite speakers, and 2-way center speaker.
Update: It's since risen in price at Amazon; it's still available at Fry's for the above price.