For less than ten dollars you can buy magnets that are strong enough to cause in personal injury, possibly even a few broken bones. Sounds like a pretty good deal, huh?
In the mid-1980ís neodymium (also called rare earth) magnets started to become available. Compared to other available magnets, neodymium magnets are the strongest permanent magnets available. Today they are used in computer hard drives, speakers, electric motors, wind turbines, etc.
As they get larger they can actually be rather dangerous. I'm actually a bit frightened by the larger neodymium magnets. If you get two of them close together with your hand in the way you'll likely break a few bones.
Other Ways to Make Strong Magnets
There are other ways to make magnetic fields without magnets. When electricity flows along a wire it actually creates a magnetic field. This can be shown by putting a compass near a coil of wire and turning the power off and on.
You can also use magnets to create electricity. One way to generate electrical currents is to drop a strong magnet down an aluminum (or copper) pipe. This also creates another magnetic field. The interactions of the two fields is The result is somewhat unexpected.
The more electricity, the larger the effect. By running large electrical currents through wire wrapped around a piece of iron you can make very strong electron magnets. These have the advantage of losing most of their magnetism when the electricity is turned off.
I'm not sure where you would buy one of these strong electromagnets but you can make your own with a nail, a battery, and some copper wire. It just won't be strong enough to pick up cars.