The vinyl you're looking for isn't silver metallic or solid grey - you're looking for 'Etchmark' or 'Etched Glass' vinyl. Try a local retail sign shop or place that does vehicle graphics. The vinyl will be slightly silver-ish, but also translucent when applied. (It usually comes on white backing paper, so you'll have to lift the corner of the vinyl sheet to make sure it's the right stuff.)
Has anyone used spray-can window frosting? I was thinking of using it. I had done my old basement window with it and the results were pretty good, and its not too bad to scrape off if you screw up.