Ending today, Beach Camera via Rakuten offers the Nest Protect Smoke and CO Alarm 3-Pack for $327. Coupon code "SAVE20" cuts that to $267. With free shipping, that's the best price we could find by $60. They feature a 120º field of view to 20 feet and work with the Nest app to send motion alerts.
Are you throwing away money? Before tossing these items that are considered disposable, consider how to give them new purpose.