Mine has a Brant 3 point immobiliser (no alarm) and it cost me somewhere around $300 for parts and fitting.
In my eyes, warm up really isn't necessary - just don't be a leadfoot just after you've started the car.
As for cool down, it depends on how hard you pushed the car earlier. 30 seconds should be okay for most times. If you've really taken your car to the limit, a 1 minute cooldown maybe preferable.