I get my Flitz here:

http://pinrestore.com/Supplies.html

Pay attention when you're buying it to make sure you're calculating price per oz - there are at least 2 sizes, 7.6 and 4 oz, or something close to 4 oz. I've found it a little cheaper online, but every time I get a source, the price gets raised. Not sure I understand why.

Interesting on the use of windex - that's something I have to try. Curious on how much of a difference the boiling water makes.