If you don't care for the expensive window cleaners on the market, you can try making your own window cleaner.

It's as simple as mixing 1/2 cup each of ammonia, water, and rubbing alcohol. That's it.  Mix and put in a spray bottle, and you're ready to go with a new window cleaner. Spritz your window and wipe it down with a lint free cloth. The solution is also good for car windshields, mirrors, counter tops, and other surfaces.

However, you should be aware that ammonia has been known to damage painted and tinted surfaces. It is not considered safe for eyeglasses that have a tinted coating, windshields with the same, or even specially treated windows. For those, plain soap and water is your best bet for your own window cleaner, or else a soap/water/vinegar solution.

In the old days, people definitely made their own window cleaner by  cleaning their windows with water and vinegar, then polishing them with old newspapers. You can still do this today, but vinegar will not cut oil or grease that may have gotten on the window, particularly in the kitchen. So if you want to get nostalgic and try this method, mix 1/4 cup of white vinegar with two cups water, and add 1/2 teaspoon of liquid dish soap, and put it in a spray bottle.

Be careful with the newspaper polishing, though. Given that many are now made with recycled papers, and eco-friendly inks, the results may not be quite what you anticipate. Just follow the instructions above and you will have your won eco-friendly window cleaner for that homemade sparkling clean window.