My fall back plan, if I just couldn't cut it myself, was to go to a small family owned glass shop and see if they would do just what you suggested, but the Dremel Wet Diamond Wheel cutting technique really was easy. Now, the difference between a first surface reflective mirror, which uses chromium, and the lesser quality mirrors, which do use aluminum or
zinc really is astounding. Even in my crappy picture comparing the two the brightness and clarity difference comes out.