Energizer Max 9V battery, 1 pack $1.98

At $1.98 this is about the best price you can get on a brand name 9 volt battery especially in a single pack and meets my $2 threshold for a 9 volt battery. Used in smoke / CO alarms, some remote controls for toys and other gizmos. You can supposedly buy in store or on line. This is not advertised in their flyer and I don’t know whether it’s a sale or regular price.

Energizer claims a 5 year shelf life, but I’m not sure I’d put a 5 year battery in a critical alarm.