Here are some ideas to help you, as I used to be on a balloon crew, and occasionally carried a scanner to listen to other crews when I wasn't busy:
123.300 and 123.500 can be licensed to hot air balloon chase crews, as well as glider/sailplane chase crews, for air-ground with their pilot. (A chase crew would be an aviation support mobile station. Part 87, Subpart K, 87.319, Aviation Support Stations.)
Otherwise, I have heard balloon crews using:
- CB
- MURS (these channels are illegal to use onboard an aircraft in flight per FCC regs, however, they are still frequently used, particularly 154.570 and 154.600)
- FRS and GMRS (licensed or not)
- Low power and itinerant VHF and UHF business channels (licensed or not, and IIRC, some channels have the same prohibition against being used onboard an aircraft in flight as the MURS channels do, but are still used anyway).
I have even heard licensed hams on balloon crews using ham radio frequencies.
Commercial balloon companies who fly paying passengers would also qualify for a business radio license of their own, or they could rent time on a local 'community repeater'. (Naturally, if they were to travel to a balloon festival out of town, they would have to have other means of communications.)
Happy hunting!
John
Peoria, AZ