I have yet to hear of a price increase from reliable sites who have close ties with retailers. For example, Canon Price Watch usually gives a one month or more warning when a price change is imminent. Retailers need time to update their web site as well as their physical store. B&H, Adorama, Best Buy, all of them will get a month or more advance notice.
The exchange rate of U.S. dollars versus the Yen has changed in favor of the Yen by about 10% over the past year, but the complex web of hedging and the fact that prices were never lowered to fully match the drop in the value of the yen make it difficult to analyze. Only the manufacturers can do that, and each may have their own situation.