Crutchfield offers the Sony XDP-PK1000 Digital Link Car Audio Sound System
with free shipping
. That's the lowest total price we could find by $400. It features a DSP (digital sounds processor) master unit, 12" subwoofer enclosure, 300-watt sub amp, built-in 4-channel amplifier, iPhone / iPod dock (works with most models), wireless remote, and more.
Update: As a reader found, coupon code "3A86" yields a free $25 gift certificate.