There are lithium-ion and NiMH 9v batteries available these days. No need to keep buying/disposing of alkalines.

Anybody who has portable test gear (voltmeters, reflectometers, laser levels) will tell you they're not completely obsolete.

And there's no point in hoarding disposable batteries. They self-discharge over time (speaking of someone who's written firmware for devices so low-powered, that self-discharge is about as good as you can get). Otherwise, I'd probably have some B batteries in a drawer somewhere (ham operators probably have a few on hand).