I think your best bet is to buy an old hard drive, one of those big fat ones from the 1980's. My friend took one of his apart and it had these SUPER STRONG magnets in it. They weren't very big, about an inch and a half long by an inch wide, but they are so strong that you can barely pull them apart when you stick them together. I've even cut my finger when I tried to hold them back since they violently pull together. In fact, one of them broke in half from snapping together so hard. They make my TV change colors from about 5 feet away. I can't believe how strong they are.