Amazon offers its Amazon Prime members the Energizer Industrial 9-volt Alkaline Battery 12-Pack, model no. EN22, for $11.10 with free shipping. (Non-members can spend $25 or more to get free shipping; otherwise it adds $5.73.) At $0.93 per battery, that's the lowest total price we could find for this quantity by $26.

Amazon Prime membership is $79 per year; however, Prime is free for college students for six months, and free for parents and caregivers for three months. (Note that currently there's a waitlist for Amazon Mom.)