I have never paid for a flashlight mount. The ones I use are free and can be found at any good bike shop. I attach the second Fenix to the handle bars via this method as well. Rain, freezing rain, sun and rough roads, I even dropped the helmet a few times by mistake right onto the flashlight.
This was my first from 3 years ago, I'm using road bike size inner tubes now, as they are small and thus look more sleek.
All you need are scissors and this video...
No need to adjust the volume, there is no sound, but then again, no sound is needed if you watch closely enough.