Experimenting with this currently:
https://store.ui.com/collections/uni...g3-flex-camera
It's 70 bucks here.
Despite the description, none of their hardware is needed to run the camera. It has an web interface - user admin, password ubnt - where an rtsp stream can be enabled.
For motion detection and recording I am using a raspberry pi 2B I had in the electronics wonder box with an open source software called shinobi. Works albeit not at FullHD, only 1080p - GPU memory of the rasPi is not sufficient for doing the motion detection at FullHD.