You can get these on ebay.
There have been quite a few G-bodies stolen in the area here and I've thought about ways of stopping it. I find most anti-theft devices are simply installed wrong and become ineffective. Most can be disabled simply by removing fuses.
Fist step is NOT to plastic tie it under the dash like most people. Hide it in the console or somewhere they don't normally look.
Once I'm closer to completion of my car I'll probably just hide a battery kill switch somewhere.. Easiest and cheapest way.