I wear a helmet when in a helicopter (ex-army hang-up I think!).
I got mine (Gentex) on US eBay - cost about USD300 with double visors, CEP and 'only worn once' - certainly I couldn't tell that it wasn't new.
I got a local (I was in Florida) set-up to check it and adjust it for my head - another 60 bucks.
It's not as quiet as a Bose ANR, but close - very close. Certainly much, much quieter than any non-ANR headset I have tried.
So, take a look on US eBay - lots on there (but know what you're buying before you bid!).
Fly safe, Sam.