Upon reading your question the thought that popped to mind was that it would be nice to use a tablet screen for that purpose: iPads and many Android screens are way better than needed.
The iPad connector is fast enough to transmit video and read/write USB2 so technically that should be doable. I assume that many Android tablets could do so too. But now getting access to that hardware is another issue.
It's possible to use the iPad as a second monitor (via WiFi) so that would be another option but would require some hardware to transform the video output of the miggy and stream it.
But in any case these suggestions are the complete opposite of cheap since they require pretty expensive tablets to begin with.