I was looking for a cheap way to add some atmosphere images to our church broadcastings.
I bought a couple of xbox360 live vision webcams on ebay ($10,= each).
This camera has a very good quality and is supported by vMix (add capture device).
The image delay is hardly noticeable.
The usb cable is 3m, but with a usb (cat5) extender you can put this camera's anywhere.
There are plenty sites on the internet with information how to replace the M12 lens.

Thats a great webcam, but it overshoot the target a little bit.
It's not cheap if you want to use a lot of them and it's HD, so you have to crop to 4:3 if your other (PTZ) camera's are not HD.
Mixing between 4:3 and 16:9 camera's in a broadcasting is not pretty.
The c920 is also 2 times bigger, so less discrete to mount in e.g. a church.
The Xbox vision cam has also manual focus, so you can focus at what ever you like for special atmospheric images.