Depends how many discs you lose, including the ones you threw in a tree to knock another one loose XD
If you aren't losing discs, you aren't playing enough.
I glued a small buzzer, battery and switch to my disc in the beginning to help track it down.
The Doppler effect was pretty sweet when you let it fly :)
I've often thought about how one could rig up such a thing with either lights or sound, but without sacrificing the pretty carefully designed aerodynamic profile of the discs. Not sure how it'd be possible without molding it into the disc itself... :)