Third Reality Zigbee Motion Sensor $12

Third Reality Zigbee Motion Sensor $12. All time low since the original release sale for these sensors. IMO the best bang for your buck since they run on Zigbee and don't populate your wifi. They also have the 2 pack (22.99 - 11.49 each) and 4 pack available (43.99 - 10.99 each).