Since the question came up in another thread, thought I would share some further info.
As noted, when we do cruises, meets, etc we use handheld FRS radios, (Typically on channel 5, no sub-codes)
The small, FRS only radios start at about $20 for a pair, theoretical 2 mile radius. You can expect to pay more for rechargeable batteries, extra features, etc. They work decently, but if we have a long convoy, the people at the front or rear may loose each other.
Example Cobra MicroTalk:
The other option on the market is a FRS/GMRS combination unit. the GMRS frequencies are more powerful, and have a much longer range. Why does this matter, you say? Some of the channels overlap the FRS frequencies, but since it uses the same hardware, the FRS channels have more power, as well. Technically, to use the GMRS only channels, you need to register with the FCC, but since I never use those, I never bothered.
The FRS/GMRS units seem to run in the $40-$50 range, and again extra features will dictate price. - The pair I picked up, the Motorola MR350, has weather radio bands, is rechargeable, both in base and by mini-usb chargers, and some other gizmos.
They all should interchange, so long as you don't have any brand specific technology enabled for channel security, or subcodes set.
Oh, and if you don't have a radio at the next cruise/meet, there may be somebody in the group with an extra that you can borrow, just be sure to give it back!