Viper alarms are modular, so price can vary widely depending on which modules you get. Plus I had mine installed in early 2012, so my pricing is three years out-of-date.
One module that wasn't available when I bought mine, but which I am thinking of adding when the budget allows, is the Android phone interface, so that instead of carrying around an alarm remote, the alarm system can text me whenever something sets it off, and I can use a phone app to arm and disarm the system. Unlimited range, as long as both you and the van are somewhere that has cell phone coverage.
Engineering: Finding complex solutions to simple problems you didn't even know you had.