Magnetic Source

Leah recommends ordering magnets from: http://www.kjmagnetics.com/categories.asp

Ring magnets can be used with fabric. These can also be sewn or riveted in fabric or bolted or screwed into a solid material. Another form of magnet attachment includes sewing conductive fabric into a pouch then drop a magnet into that pouch. A clasp magnet (like used in jewelry) is another type that could be attached by sewing onto fabric.
Note: K&J magnets are extremely strong.