My local hobby shop has the Estes E2 Tracker for 30.99. It looks like a
large hand gun with an LED and compass mounted on top. It comes with a set
of head phones and a "transmitter" that fits in most body tubes.
I was not able to open and inspect the transmitter, but it looked like a
simple sonic beacon (i.e. it makes noise). If that is the case, the
handheld device is nothing more than a audio amplifier with some sound level
intensity driver circuitry for the LED.
Is this transmitter RF or sonic? The box states a detection range of 200
meters. This type of range specification is typically used with RF
transmitters (in that your "hearing" is not a factor in the range).