PC Richard has the Philips HTS3531/F7 300W 5.1 Home Theater System for $80 with free shipping. Features 300 Watts of total power, HDMI putput, DVD player, Dolby Digital 5.1 surround and Music iLink for connection to an iPod/iPhone. Walmart also has it for the same price with free site to store shipping.
These budget Philips systems are pretty good for the money. Just don't expect miracles if you're trying to play HD content through the USB port.