Ysmile via Amazon offers two Diaotec Ultrasonic Pest Repellers for $19.99. Coupon code "VDH55576" cuts it $13.39. Plus, Prime members bag free shipping. That's $6 off and the lowest price we could find. This device claims to repel mice, roaches, and other pests via 20kHz to 85kHz changing ultrasonic sounds. It features a night light and coverage up to 1,950 feet. Deal ends January 31.