I've got a Viper 550 ESP in my truck, and just put one in my 'rents new jeep. I love it, rock solid system. Can be used as a remote starter and auto window roll up system too.
Try searching one out on ebay, thats what i did last time I bought one...think I paid about $180 but that was a while ago and I really dont remember lol
Any of the newer, more expensive stuff is really just the same old technology just repackaged...not worth the $$ in my opinion...
The best is a hidden kill switch. I watched a test where they had pros try to steal a car. The car had an alarm a club and a kill switch. You had to turn the key while touching somthing like the cigarett lighter or a screw holding your door panel on ect. They would have the car open, club off and alarm diaabled and the car hot wired withen 30-40 seconds. Could not start it though because of the kill switch. They said they would have to spend forever trying to figure out how to bypass it. The best part is you can have it done pretty cheap. less than $200 bucks.