Look, as far as I understand, after accepting the order, Canon ( or the retailer ) should be legally bound to taking the agreed contract price for the product. I mean... I fully understand the changes in world commerce, and companies having to pay higher interest rates to keep up their financial health with banks loans and changes in production cost simply for currency exchange rate changes and so on. They COULD have done a "from now on, due to the international crisis, we'll be forced to increase our product pricing", but you'd have to know the full price the moment you order. After you ordered, I feel they should be obliged to honor their word and advertisement. Say, if when your ordered, your order receipt says "$500", and they charge "$600", I would go for a lawsuit to have them honor the price I bound myself to pay, when ordering. Unless you signed a contract saying the prices are subject to changes and so on, and you agreed with that.
I think it's not worth the hassle to debate with your retailer, but it's worth taking your receipt with the price, and the receipt for the charged price, and enter a class lawsuit with all photographers who feel this isn't fair, to change price after the purchase is done. Maybe you're up for a refund and you'll be teaching Canon a lesson.