Kokorest via Amazon offers the Meterk EMF Radiation Detector for $38.97. Coupon code "RMAG5WCT" cuts the price to $19.87. With free shipping, that's $2 under our December mention and the lowest price we could find by $10, excluding the mention below. It features an LED-backlit LCD, sound/light alarm, and range of measurements. Deal ends August 15.

Don't need it soon? Domecool via eBay has it for $18.32 with free shipping from China. It should arrive in two to six weeks.