Amazon offers the Marantz Slim Line 5.1 Home Theater Receiver, model no. NR1403, for $299 with free shipping. Outside of the mention below, that's the lowest total price we could find by $100. It features five 50-watt channels, Audyssey MultEQ (Bronze), 3D pass-through, and six HDMI inputs.
A close price: Crutchfield charges $299.99 with free shipping.