After a brief recall, the Nest Protect carbon monoxide and smoke detector is once again available for sale, this time at a $30 discount. It's still more than your garden variety smoke detector, but boy is it awesome . [Nest Protect, $99]
Apple's AirPort Express and AirPort Extreme aren't the most customizable routers out there, but they're dead simple to set up, and are generally very well regarded.
Refurb Apple Airport Express ($60) | Groupon