Select Home Depot Stores have Airthings Wave Radon Battery Op. Smart Radon Detector (2951) on sale for $109. Shipping is free. Otherwise, select free store pickup where stock permits.
Note: Price & availability may vary by location.
Thanks to Community Member Jeremy060 for finding this deal.

Features:
Access both long- and short-term radon results straight to your smartphone app via Bluetooth or easily generate a radon report through the Airthings dashboard.
Simply wave in front of the device to receive a color-coded visual indicator of the overall air quality: Green (Good), Yellow (Fair), Red (Poor).
Airthings Wave Plus works with Alexa, Google Assistant, and IFTTT (if, this then that)
Wave Radon can be added to a network of Airthings devices (purchased separately) for multi-room monitoring. Must be used with an Airthings hub product such as View Plus, View Radon, View Pollution, or Airthings Hub.
Wave Radon is a battery-powered, smart radon detector that monitors radon gas, temperature, and humidity in real-time.
Includes: Airthings Wave Radon, 2 AA batteries, Quick Start Guide, Airthings Support & optional and (free) extended warranty to increase your standard product warranty to five years.