Etekcity via Amazon offers the Etekcity Wireless Doorbell Kit for $18.98. Coupon code "4BQVO79W" cuts it to $12.99. Plus, Prime members receive free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping adds $6.94.) That's $2 under our June mention, $12 off list, and the the lowest total price we've seen. It features a wireless range of up to 1,000 feet, 52 chime options with four volume settings, and flashing LED alert.