Meet the TIVDIO WiFi Video Doorbell: a smart door phone with a 720p camera that lets you answer your door from anywhere and see/speak to your visitors from your smartphone. It can detect when someone is standing at your door even if they don’t press the bell.
The camera has a 60-degree viewing angle and night vision. You can mount and sync the device to your router easily. Costs under $90 at this time.