Elevation adjustable scope mount/base - why no makers?

I am surprised that with all the aftermarket parts wizarding and such I do not see anyone making an adjustable elevation scope base/mount such as
these:

http://bulletin.accurateshooter.com/2013/08/cold-shot-scope-base-dial-adjusts-from-zero-to-150-moa/

http://bulletin.accurateshooter.com/2010/10/ivey-externally-adjusting-scope-mounts-for-ultra-long-range-shooting/

http://bulletin.accurateshooter.com/2007/07/external-adjusting-rings-for-ultra-long-range/

I see so many complicated and ingenious fabrications by fellow airgunners with a lathe/mill etc... I think there is a market for some simple precision adjustable MOA mounts for under $100.

 
The problem with a single-piece scope mount is that it would obstruct the magazine on many PCPs.

In search of cheap, I recently bought these rings from Sun Optics USA. I haven't had them out in the field so I can't say much about them yet. My initial impression is that they serve a different purpose than the FX No Limits rings. The FX rings are for making large elevation adjustments in the field. The Sun Optics rings are for making smaller adjustments in both elevation and windage, but not (easily) in the field.