First thread, please be easy on me!
Amazon has Samsung SmartThings sensors for $20 each.
Samsung SmartThings Multipurpose Sensor $19.99
https://www.amazon.com/dp/B0118RQ…lAbYK
Samsung SmartThings Motion Sensor $20
https://www.amazon.com/dp/B01IE35…lAb2X
Samsung SmartThings Water Leak Sensor $20
https://www.amazon.com/dp/B00MOIY…lAbDK