Update: Deal over.

2 Pack Of ecobee SmartSensors – Link

Amazon has this currently marked down to its lowest ever at just $53.99 w/ free shipping.

• WHOLE HOME COMFORT: Works with all bee smart thermostats to sense temperature beyond the hallway, ensuring better comfort in the rooms that matter most.
• TARGETTED COMFORT: With built-in occupancy sensors, you can trust Smart Sensor to keep you comfortable wherever you are and in the rooms you actually use.
• ENERGY SAVINGS: When Smart Sensor detects that you’re not home, it signals your bee smart thermostat to automatically adjust the temperature for better energy savings.
• INSTALLATION: Works with all bee residential smart thermostats. Activation takes seconds.
• REDESIGNED: An enhanced look for enhanced performance, detecting occupancy and temperature faster and from further away.