I don't know if you can order through Amazon, but they list Duralar Wet Media in sheets and rolls. It's not a photographic product, per se. Have you tried art stores? That is where I bought mine. If they don't recognize the Graphix brand, talk to them about wet media mylar films. It seems that critical thing you are looking for is 4 mil (.004 inch) thickness. (I don't know if or what the metric equivalent is.) If you can find a 4 mil wet media film I believe they are all really the same, or very similar, material.

-- jason