I'm not sure why you would bother. The broadcast range wouldn't be very far (those fm transmitters are usually rated in feet), and the quality isn't very good.
If you're looking for something cheap, pick up some FRS radios. Can be used to communicate between vehicles, or out in the woods between parties. The relatively low power means if you're out of populated areas, you aren't likely to find anyone else on channel listening in.
For higher power transmissions... parties involved could get their amateur radio operators license, and communicate on various types of equipment, take advantage of local club repeaters, internet echo-link communications, or longrange communications. Yes, more expensive to purchase, but it'll gaurantee you more than 5ft of transmitter power.
If you're looking for something cheap, pick up some FRS radios. Can be used to communicate between vehicles, or out in the woods between parties. The relatively low power means if you're out of populated areas, you aren't likely to find anyone else on channel listening in.
For higher power transmissions... parties involved could get their amateur radio operators license, and communicate on various types of equipment, take advantage of local club repeaters, internet echo-link communications, or longrange communications. Yes, more expensive to purchase, but it'll gaurantee you more than 5ft of transmitter power.
