You can get a Lot of 10 of the Iris v2 3326-L Motion Sensors (new) for $50 plus ~$18 in shipping from the following site. Add a Lot of 10 Iris v2 3320-L Contact Sensors for another $50 and the shipping cost barely changes. So, for about $120, you get 20 Iris v2 Zigbee sensors, or $6 per sensor. Hard to beat that. Get then while they last!