(Fake) Alarm LED

I've been thinking of Radio Shacking a phony alarm led hooked up to a 9-volt battery and switch for my AE102 but I realized that there may be a ready-made retail product.

Does it exist?
I'd rather have a stand-alone unit than tap into my car's switched power source.
I have seen those hardwired LEDs sold along with DEI shock sensors for my e46.

yeah, they have all kinds of them, some of them are just addons but you an just hook it up to you batt and a switch and ta-da! fake alarm led