The answer may surprise you:
That's right, folks. Just regular ol' club soda that you buy on the soda aisle in the grocery store.
I simply put it in a spray bottle and Voila! You've got easy, cheap, and cleans-way-better-than-Windex mirror and window cleaner!
Directions are easy: spray onto the surface and wipe with a microfiber cloth.
It is streak-free and has no odor. I even used it on my car windows and windshield (inside and out). It cut through all the saltwater grime left on my car after I washed it. If you have ever lived in Florida, you know how nasty your car can get. The club soda cut right through all the grime and left my windows spot-free!
Don't worry if it loses some of it's fizzle - the spray will still work its magic.