Here is a link to a thread that discussed this question.
(there was a url link here which no longer exists)
Here is a post I made in that thread in an attempt to try to estimate the likely price rise.
"Based on the current price of silver (about $1 per gram) and the amount of surface area in a roll of 35mm film (I estimate about 0.055 square meter) and about 6.5 grams of silver per square meter (midpoint of the estimates given in earlier post) I estimate a roll of film contains about $0.36 worth of silver. This represents something like a $0.14 increase over the previous year average price, and perhaps a $0.18 increase over the five year average. If we assume that the markup over the cost of raw materials is perhaps threefold (please supply a better number if you have one) then one might expect the cost of film to increase by about $0.50 per roll. If the markup is six fold then one might expect an increase of about $1 per roll..."
I think the announced price rise is within this estimated range, near the high end, or perhaps just a bit outside the high end of the estimated range.