Some years ago, I got something called the Helmet Hook. Like most guys, I've dropped my helmet or rather, all my helmets and got fed up. To make a story short, this thing is cheap, super easy to use and solves the problem.
It's a plastic hook that you attach to the end of your handlebar and you need something that will hold it in place. Bar ends or handguards. It has a metal washer that can be removed if you have the type of bar weights that have an expanding bushing which are pretty thick. If not, you leave the washer in place. Most bar weights are bigger than the opening of the helmet hook and when tightened, will keep it in place. If you have handguards, you may even be able to rotate the hook out of the way if you are so inclined.
The thing is around 15 bucks and with around 2-3 bucks shipping is still cheaper than a new visor and let alone a new helmet. You can attach it with your d rings, even if you have a quick release strap or ratcheting attachment. In short, EVERY time of strap/attachment will work. It's in the best possible position unlike a helmet lock which is usually close to the frame where it might get dirty, close to the engine or exhaust and so on.
Also, you don't have to get off the bike to unlock anything.
This isn't lockable per say but you can buy a padlock from them the slides through two holes and thus locks the helmet.
It was never meant to do anything but to give you a convenient and easy to reach place to hang your helmet rather than having to hold it, hanging it on your mirrors or something else.
It's one of those things that you don't know how much you'll like until you've had one.
I don't have a way of taking pics but I'll link to some on their site which is TheHelmetHook .com in one word (I dont' have the post count to post links yet) and although they are slow on updating customer testimonials, check the one from Michael in California on their testimonial page.
They also had a review in the Australian online magazine Traverse which I was going to post about somewhere here (the magazine that is). I just realized I can't post links so just do a search for Traverse Magazine.
I've used the hook for a long time so ask if you have any questions or just contact the company. They are super responsive and the hook has a lifetime warranty if you break it. Normally it should be under normal use but they are very liberal with that.
If you have any inclination about locking your helmet, get their padlock 'cause a suitable lock is hard to find. Trust me on this.
Note that on bikes with short handlebars like these, when you hang it, it can touch the side but as long as you hang it carefully, there won't be any damage to the fairing. Just a heads up though.
Plenty more pics on their site.