How kind of walkie-talkie should I get?

Me and and my two friends are going to PAX Prime and we are all wearing helmets. We want to install something into the helmets to allow us to speak to each other without having to shout. Is there a type of walkie talkie that will allow us to speak to eachother for roughly $60 or less. Oh, and it has to be able to talk between three people. Thanks for the advice!