CSHope via Amazon offers its CSHope Waterproof Wireless Doorbell for $15.99. Coupon code "ZSJGZBA4" knocks it to $13.59. With free shipping for Prime members, that's the lowest price we could find for this doorbell with sufficient stock by $11. It features a 1,000-foot wireless transmitting distance, 36 ringtones, 4-level volume, and LED.