With the prices of the specialized units, I think it's going to be cheaper to get 2 or 3 (multipack) two way radios, and two throat mics. I am semi kicking the idea around to just wait till after the ride and build my own setup either via some tx/rx kits, or find the chips and build my own board w/ throat mic combo.
Sure would be fun if there was a radio band setup for cyclists and everyone could tap into it via a "cheap <$35 per radio" - and setup their own private channels if they wanted to split off from general chat.
Also would like to have a party line function. Not sure if there's a way to do it to get everyone's communication into a single channel talking at once (interference) without multiple tx/rx bands or a server to process 'em all and resend to a common band, ie. three way calling - hm that might be possible - two TX and two RX's per radio set (or the ability to talk to two separate channels), then can link them without a server and just relay the transmissions from other radios on that second transmitter receiver or second channel.
Radio 1 & Radio 2 Linked (radio 1 constant tx1a to radio 2 rx1a, radio 2 constant tx1b to radio 1 rx1b)
Radio 2 Links to Radio 3 (radio 2 constant tx2a to radio 3 rx2a, radio 3 constant tx2b to radio 2 rx2b)
Radio 3 is relayed thru Radio 2 to Radio 1, Radio 1 is relayed thru Radio 2 to Radio 3
etc. Each new radio can then link another radio with up to 2 radios per set in a "party line", and to make things easier to setup you could have a setting for each radio to "auto-link" automatically send requests and receive requests if it has a free line available (able to switch this function off). This would allow everyone to chat at once (granted there might be some lag, but probably very little). With a little more thought and if a data packet was available, channels or bands could be changed and the links re-established based on who has the better signal strengths.
rider 1 here............................ rider 2 here........................ rider 3 here
rider 2 here.......................... rider 1 here................rider 3 here
Granted it's more complicated the more riders you add, though could be an interesting way for some social networking among cyclists.