I just got this, I think it's an incredible deal, no expansion though.
4 Indoor/Outdoor Rated 600 TVL Cameras, PC and MAC Remote Viewing, IPhone, iPad, Android, and Blackberry Viewing via Free App, 120' Night Vision, 60' Cable Per Camera
4 Channel DVR
500GB Hard Drive included
PC and MAC Remote Viewing
IPhone, iPad, Android, and Blackberry Viewing via Free App
4 indoor/Outdoor Rated 600 TVL Cameras
120' Night Vision
60' Cable Per Camera Included
What can you see about 120 feet away in the dark? - Probably not much. Let the four included security cameras in this bundle do the work by capturing detailed activity with a broadcast quality D1 view. The cameras are equipped with an infrared cut sensor, 600 TV lines of resolution, 42 infrared LEDs and a 120 foot night vision range. With the included 500GB hard drive, you can save numerous hours of video, and the industry-standard H.264 video compression allows for maximum recording time while minimizing file size.
Video is captured in real-time, broadcast-quality D1 704x480 pixel resolution at a rate of 30 frames per second (per camera), which results in smooth, continuous video motion and a larger D1 video image for improved recognition of people and objects.