Mouser Electronics has available Murata’s AMR (Anisotropic Magneto Resistance) Magnetic Switch Sensors.

These switch sensors are non-contact magnetic sensors of high sensitivity for use in a relatively low magnetic field in either a vertical or horizontal direction.

With no mechanical components, AMR sensors are more reliable and robust than Hall Effect IC's or reed switches.

Murata's AMR Sensors are used in consumer white goods, industrial and security equipment. A range of sensitivities are available. 

http://www.mouser.com/murataAMR/