There are several systems that are available in the $10 to $20 range, but they mostly work on an audible alarm principle. Basically they include a small speaker that emitts a loud beep or alarm when the receiver loses contact with the transmitter.

The idea is to walk out toward where the plane is and shut off the transmitter once you're in the vicinity. The alarm is powered by the flight battery, so it won't last forever. You also have to hope that the battery and/or alert device weren't disconnected or damaged during the crash.

The older fella from your club probably just meant that he'd go out and use his GPS locater to make sure he was searching different areas instead of trekking across the same ground over and over by accident.