I used the EM-408 from sparkfun for a university project. Great little device; easy to use and surprisingly accurate.
However, you'll probably end up spending more than just the $60 after all the extras are bought. In my case I also bought a bunch of the surface mount connectors, and the magnetic external antennae, and the pigtail that converts the external antennae connector from mini-ccx to ccx. After buying three modules with all the extras and shipping, it worked out to be about $100 per unit.