The Cleaning House is selling a quart sized, industrial strength spray bottle full of great window cleaner for around $4.79.  The best part of the deal is that they fill it up FOREVER for FREE!   I have not heard this advertised anywhere, but I went there and they told me about it.  And sold me on it!  Read article in my local paper about the company below.  

http://www.lubbockonline.com/stories/020408/bus_243478100.shtml

And see another article that tells more about their locations.  http://www.write2us.net/coupon/2009/04/22/free-window-cleaner-forever-again/