Today, January 21st only, on Amazon where they are offering this
Corentium Portable Home Radon Detector for only $99.99 shipped (regularly $168.08) – lowest price!

This portable radon detector allows you to test radon levels anywhere you are. It features an LCD screen that displays the average daily, weekly and long term concentrations. Easily take measurements from one room to another in order to get an overview of the concentrations of radon in a home, workplace, school, daycare center or any other location!