Here’s a nice deal over at Amazon. Right now they have this First Alert Smoke Detector 6-pack on sale for $45.49. That is only $7.58 per device. These are hardwired detectors with battery backup. Here is the link to the item:
First Alert Smoke Detector 6-pack – only $45.49 ($7.58 per device) while supplies last at this price
$7.58 per device!/First Alert Smoke Detectors!