Linger via Amazon offers the Vensmile Ultrasonic Pest Repeller for $35.90. Coupon code "E6J65XNH" cuts it to $22.26. With free shipping, that's the lowest price we could find by $20. This device repels mice, roaches, and other pests via a high impact pressure wave and ultrasonic sounds. It covers areas measuring 5,000 to 6,000 feet.