Dukane has announced a new RF wireless microphone. The US$249 Dukane WM1C1 is a RF based wireless microphone system that includes receiver, transmitter, two microphones, lavalier and charging device. 

It has 80 separate RF channels so school buildings will be able to install the wireless mic without fear of cross talk.  The WM1C1 can be installed in an existing projector with a mic in port and larger speakers. For more info go to http://www.dukane.com/av/products/documents/specs/WM1C1.pdf .