Fake 'Car Alarmed' Light?

My girl's car was stolen recently. We've since replaced it. The new car is supposed to be alarmed. (Honda Civic 1999). This may be true, but there's no visual thing to tell thieving scrotes that it's alarmed. I need a cheap, battery operated red flashing light (just one or two, not a set of Christmas lights) that we can put in the car to deter the thieving slimy slugs. Can anybody please tell me where I can get one from? The only one I can see is in America, and I'm not paying $18 or whatever to have one shipped in. A review says it's rubbish anyway. Any help greatly appreciated. .... Thanks