Be meter free
It is important to note that reflected light meters aren’t as clever as the educated photographer when it comes to exposure compensation. Expecting to see an average scene, reflected light meters can be easily fooled and will give too short an exposure for a predominantly light subject, and too long an exposure for a predominately dark subject, resulting in images that could be up to 2 stops off the result the photographer had envisioned. The good news is that vintage mechanical cameras work perfectly when operated manually without batteries, and only need electronically powered light meters to operate in Auto mode.
An understanding of the relationship between film speed, aperture and shutter speed settings not only liberate from needing a light meter but give you creative control over your photos. There’s a romantic ideal about knowing what you are doing without relying on electronic circuits. Legends such as Cartier Bresson didn’t need a battery to capture his ‘decisive moments’ and usually estimated exposure, as was routine practice. Vacarro had to think quickly in potentially deadly combat situations.
If you know what you’re doing, if you understand the principles of photography, you can be self sufficient. There’s no need to worry about batteries being discontinued; a mechanical camera and knowledge of fundamentals are all you, your children and your grandchildren will ever need.