Silver prices may fluctuate but I don't recall film and paper prices dropping once they rise. Could be that the manufacturers are selling fewer rolls and sheets while the cost of production of which the silver is only a portion and advertising etc has increased. Film costs less in the US probably because the sales tax is lower. In 2005 a roll of Delta 400 120 was $2.99 (I have an old catalog) and now $4.12 a 4% increase. I'm not sure what that tells us other than stuff has become more expensive.

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