They're known as NIB and can be found endlessly on eBay.
Otherwise, bust open an older disk drive that is junk to you. The NIB is used on the swing arm as a DC-Stepper.
They're best used as stud finders. If tin you're golden, always.
If wood then you're going for the nails/screws. I've found manny an install that skips studs like crazy.... to include exterior insulation!
http://www.youtube.com/watch?v=9movZLFc_ZkThere are a host of videos at the above link.
