Have a look at.....
< http://www.timberwolf.com/masterwolf/electricity.html >
This has a citcuit for a simple device that you can make yourself. There are a couple of confusing parts listed from the Radio Shack catalogue. The MP2955 PNP transistor (listed ad unavailable) should be a 2N2955 which IS commonly available. The NPN transistor listed as an alternative should be a 2N3055, which is also commonly available. The rest of the parts are also no problem.
Good luck with your search,
Dennis.