IIRC the USMC/Navy helo pilot's helmet 1974-78 time frame was about $300.
The helo helmet was a dual visor and a bit heavier than the fighter pilot helmet. They had a single visor which had to be swapped for night flying. We had both stored in the helmet at all times.
It weighted about 3 lbs, IIRC.
Thanks, I traded a newer model for some knives around 1982.