No pictures of this one yet either.
We had decided we wanted to do a startle as soon as folks walked onto the property.
We actually redo these things every year or so, but the actual idea is pretty much the same. The only really difficult thing you will need to track down is a PIR sensor. That's a motion detector to you and me. Radio Shack sells them cheap enough. Get to get one that runs on DC low voltage (made for burglar alarms), it will make things sooo much easier.
We started out with those cheesy screaming doormats, but just about anything that makes noise when triggered is good. Keep in mind that whatever you buy, you are going to cannibalize so you really wouldn't want to use something that works well by itself, or that is expensive.
Slice open the doormats and remove what's inside.
Splice the motion detector into the device and put it in the middle of the bushes. On a windy night you'll have to move it closer to the outside (the moving bush will trigger the device instead of TOT'ers.
That's really about it. It's not very complicated, but it makes for a great effect.