@ ccolewilliam

I think you'll find that the cameras being used with vMix are all over the map from simple Webcams to hi-end 4K broadcast cameras, a lot depends on what kind of budget you are looking at. Certainly, many mid-range and consumer cameras offer HDMI output while most of your higher end cameras will have SDI output. Since most of your work is greenscreen chromakey, I would explore and research cameras in your price range that have exhibited good results with such and go from there (I would recommend larger sensor cameras and/or 3 chip cameras, but here again is where budget comes into play, a decent DSLR or Blackmagic Pocket Cam might be the right fit over a consumer handicam).
In terms of video capture hardware, once again, you have many options which to a large degree depend on your camera output so I would spend time here: http://www.vmix.com/soft.../supported-hardware.aspx once you narrow down your camera choices.
On a side note, I am very impressed by the work you are doing (somewhat amazing with just vMix and a webcam) but as I'm sure you've come to realize, broadcast quality comes at a substantially higher price for what is often only 'marginally' perceptible by most people.
Keep us all posted as to how you make out.


Ice