Cafago offers the Meterk Electromagnetic Field Radiation Tester for $26.76. Coupon code "E2470J" cuts the price to $15.30. With free shipping, that's $41 off list and the lowest price we could find. It tests the electric and magnetic field radiation and features two temperature units, an LCD display, sound-light alarm.

Note: This item ships from China and may take up to four weeks to arrive.