Altatac via eBay offers the Optoma 720p 3D DLP Projector, model no. W303, for $399.99 with free shipping. That's the lowest total price we could find by $129. This DLP projector features an image size of up to 300", a native resolution of 1280x800, 3,200 lumens brightness, 15,000:1 contrast ratio, 3D compatibility, and HDMI.
Update: Specs corrected.