I'd have to mirror what PrecisionPhoto and Gerry Szarek have said about the pre-production costs. Sure, it probably costs Canon at most a grand to make a 1Ds Mark III, but then you have to amortize the design costs, the marketing costs, and thanks to the initial ID Mark III glitch, the damage control costs.
Apparently the Canon CPS price for the ID Mark III in Canada is $4200. One major store I talked to has the camera store I chatted with offered me $100 off their list price of $4599, and showed me the dealer cost of 4200.
Clearly sales volume matters in terms of what sort of dealer price you get. You also have to take into account the cost of maintaining the distribution system and getting the cameras through the different regulatory/customs procedures. These last two things explain a lot about why Canon gear is cheaper in the U.S. than anywhere else. Simply put, my friends to the South have a much bigger market and a whole lot more money to spend than we with the polar bears do, or my friends with wonderful social safety nets in the EU.
Canon Canada is owned by Canon USA and that's that. Commercial colony, and don't blame french on the box either boys. I don't care if people talk about how Canon can manufacture the stuff just don't go cranking Ben up by telling him he's making 45% per camera