I picked up a used aircraft intercom box on one of the auction sites, then later found a deal on the expansion box for it. It allows me to run 4 headsets. I put the expansion box in the rear of my deuce to allow anyone riding on the troop seats to communicate with the cab. This was very affordable, as opposed to buying a new unit. My headsets were also bought used. Another advantage to the aircraft intercom headsets is their ability to noise cancel, which is a good thing in a deuce. Don't rule out an aircraft system, they are available used all the time, as people get out of flying, and those who rent planes to fly will have their own portable intercoms. which they will take from plane to plane. My unit is one of these portables.