While not the cheapest, the best wifi camera I've found so far was to build one from a RasPi Zero W, and install motionEyeOS on it. From there, you could add s

While not the cheapest, the best wifi camera I've found so far was to build one from a RasPi Zero W, and install motionEyeOS on it. From there, you could add simple motion tracking (OpenCV or something like that - there's enough in the distro to easily do blob tracking) and command a servo to track. Total cost for the basic camera setup (not the tracking extra) was around $60.00 - and you don't have to pay for a cloud service or anything like that (I just have it email me the images), plus it's open source, so you can vet the codebase if you need or want.