One of my cousins just bought a fairly new used car. He was worried about hitting kangaroos on some of his longer drives so purchased a Roo Shoo (I think thats the name). Im not sure how much it was, but I think it was fairly cheap. He said that the first drive he went on after installing it, a kangaroo jumped straight out in front of his car. Lucky for him he didn't hit it. Now I can't really say they don't work because he is the only person I know that has one, but they certainly don't seem like a foolproof way of avoiding wildlife. But if you can get them for as cheap as some of you guys have seen them, why not give it a go.