Here is another WiFi doorbell that lets you see who is knocking on your door from your iOS or Android device. The YAMAY WiFi Digital Door Peephole features PIR motion detection, infrared night vision, and video recording capability. It allows your visitors to leave you a message before they leave.
This smart doorbell has a 3.7″ LCD screen, 130-degree viewing angle, and iOS/Android support. Costs under $185.