You could also try used sail boat
equipment dealers, there is a boom on Latatude 38 right now, but at 17.5 feet too long.
Rigging shops some times have used booms and masts kicking around. Boat movers with
storage yards also get this kind if thing off of boats that are abandoned in their yards. Hope this gives you some ideas. I bought mine from a classified add on Latitude 38, 12 years ago. not sure where you are located, but I know of several places in
California where you could call and inquire.