I use 312 size batteries.Costco has there own batteries. They are called Kirkland Batteries. Reading the package, the batteries are made in the USA. The package has a guarantee that the battery meets or exceeds all national brands. If you are not satisfied, you will get a full refund.
I purchased a pack of 40 for 8.99. That averages out to 0.22475 cents per battery. In the past I have paid anywhere from an average of 50 cents to 75 cents per battery.
I am presently testing the performance of the batteries. I usually get @ 5 days use on a battery. If they are as good as the other batteries,then the savings would be more than half my prior costs of batteries.
I will keep updating on using the batteries.