Amazon offers its Prime members the Kidde Dual Sensor Smoke Alarm with Battery Backup
in White, model no. PI2010, for $20.07. At checkout it drops to $17.06
. With free shipping
, that's the lowest total price we could find by $20. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.59.) This hard-wired alarm features both photoelectric and ionization sensors, hush feature, battery backup, indicator LED, and more.