Good point 3D:

For really long range finds, measured in miles, there is the Walston system. The plane unit is about $150 and the tracking unit is hundreds of dollars. This is good for clubs, especially glider clubs where the club buys the tracking unit and the members buy the tracker. If your glider costs $1200, a $150 transmitter is worth the cost.
http://www.texastimers.com/helpful_h.../wal_cover.htm