If your windows aren't already 'glazed' (i.e. fitted with glass), you must have a very draughty house!
;-)
I'm guessing that you're referring to 'frosted window film'. If so, try googling for that search term and then clicking on the 'Shopping' button. (You can order the results by price from the drop-down menu). One of the places that will lead you to is here:
http://www.avenuesupp...rosted+film&go=Search
(Note that there are several different sizes. Click on the best size for your needs, in order to get a price).
If that's not exactly what you're looking for, do the same again but simply looking for 'window film'.
Chris