This product is available through a Sears distributor. $24.99
It might have some use as a triggered audio player. Looks like a large built in speaker. I'll bet with slight modification you could wire an audio plug to have it play the audio off a cheap player whenever someone approaches. The price is about what HD charges for a light sensor.
Regardless of the hack...I could use one of these to shoo off skeeters when I'm prop building outside in the evenings. 5,000 sq ft range?....hmmm.