Cambond via Amazon offers its Cambond Waterproof Wireless Doorbell Kit with LED Flash in Silver for $22.99. Coupon code "CAM2BELL" cuts it to $16.99. Plus, Prime members bag free shipping. That's $6 off and tied with our July mention as the lowest price we've seen. It features a 500-foot wireless range, one transmitter, two plug-in receivers, and 58 ringtones. The transmitter requires a CR2032 LiPo battery, included. Deal ends September 18.