Gun locks are pretty steep, but they come with a free gun.*
I do use one when I go to the gym. (gun lock) Definitely not super secure, but works great to prevent thefts of opportunity. Personally, my helmet never gets left on my bike for an assortment of reasons. I do wonder why Yamaha didn't install a helmet lock. My old ass FJ has one. Probably a cost cutting move.
*except in California.