I've found ones basically like this down to $5!
Where the camera is listed as 1/9th inch, it seems this is a 0.3Mp camera, and only supports 640/480 resolution.
Where the camera is listed as 1/6", then the spec might be 0.3Mp or 640/480 for an Android or other smallish screen, or 1.3MP or720p or 1280x720 for a laptop or larger. 7mm seems to be the narrowest head for these.
However, how about a head like this?
Of course, that is an order of magnitude more expensive - $350. But airplane mechanics are starting to use those. They list the old standard 640/480 as their resolution, but it may be that more isn't needed?