As I stated earlier, I can understand the cost for film. But besides film, I also purchase silver nitrate, gold chloride, potassium chloroplatinite and sodium palladium. It's their cost that has not budged with the declining market prices.
Probably because your supplier's costs don't turn on a dime, either. The big drop in commodity prices has been just in the past few weeks. Your suppliers may still be using materials they purchased (or bought contracts for) prior to that.