Talking about spooky store scores and online oddity offerings.
American Science & Surplus ( has a motion sensor w/ different scary sounds & lights that's meant to go inside a jack-o-lantern, for 7.95. I'm sure it could be used in other ways, too. They have some neat stuff at this site, and you can sign up for e-mail notices when something you might be interested in arrives or is on sale, which is how I found out about the sensor. I've ordered several times from them with no problems.
I saw something likes this at Five Below this year, but it was not as good sounding as this one. I do not think you could set what happened when the sensor was triggered on the Five Below on.