The microscope has been a wonderful device for many undertakings. Surface mount electronic building got me started. There are lots of good scopes on the auction sight and this one was about $75 four or five years ago.
The limitation to visual observation with the scope stems from the lighting source and angles so anything viewed is only relevant to identical equipment configurations which in my case is manageable. The face is a far better measuring device than any visual observation as so many others have pointed out numerous times. Shave ready isn't nearly as valid as shave tested and shave tested on my face well YMMV. :hmmm: