The vast majority of SAR units are volunteer. The radios they use are fire/law enforcement issued and on designated channels. HAM is your best route if there are repeaters in your riding areas. You can get a multi band 5 watt radio pretty cheap, you do have to be licensed to use anything over 1 watt. Someone is generally listening on the HAM channels because that user group are radio hobbyists. You can program in your local first responder channels on those radios, but you will not be able to transmit, even in an emergency. There is a built in blocker in these radios. You can listen though. Our local area in central idaho is promoting using/ scanning 9.11 on the family band channels with the hope someone could be close enough to hear a call for help. In the mountains, range is limited. Our 700 digital radios have been working pretty well though.