If you have power and fast internet you've got some great options that aren't ridiculously expensive. I've got several power-over-ethernet PIR (passive infrared) cameras hooked up to a wireless router with a verizon 3G card. I get instant photos or videos on my iPhone, day or night, whenever the cameras detect motion. As an absentee owner, I can call my good neighbor who will jump in his car and intervene. And I have clear photos/videos of the perp which I use to prosecute. So far I've taken one person to court and he got slapped with a $175 fine and a warning. Word's out in the neighborhood that I don't play.
