$210: viper 791xv.. 2x shock sensors, motion sensor, hood sensor, trunk sensor, door sensors, outside and inside siren, 2 way pager, remote start, backup battery. i installed it myself and added an ignition kill.

no matter what car alarm you have however, if a theif wants your car (turbo, rare engine, lots of custom fab) bad enough.. they will just drill through the fender/battery and drain it, then open the hood, disconnect the alarm, put a new battery in. this is why i would also highly recomend a backup battery ($20) for the alarm if your car is a big target.