1byone Products Inc. via Amazon offers Prime members the 1byone Wireless Home Security Driveway Alarm with two Sensors, model no. O00QH-0519, for $25.99 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $5.13.) That's $17 off list and the lowest total price we could find. It detects driveway movement up to 26 feet away and features sound and light alerts. Deal ends March 24.