Not sure of the cost. I just skimmed the article in the Polaroid issue of _VC_ mag (sept/oct 2001) and didn't find it, but I know I've seen it somewhere. I don't think there's much reason for Polaroid to list the materials on their website, since the market is so small. Anyone who needs 20x24" is probably on a first-name basis with the Polaroid folks (or they ARE the Polaroid folks).