From the man in a black trenchcoat at the corner of the street. It's not always about getting the lowest price. You will want to feel safe and assured of your purchase too. That's the reason I always recommend buying onsite from a reputable store near you. Peace of mind comes with a hefty price all well worth it.
BH Photo, Adorama, and Amazon are competitive in price. You may sometimes see one a little less than the others, although usually not for long. You will rarely see someplace reliable beating them. If you see someplace beating their prices by a lot, it is probably a scam. There may be an Asian vendor that is not an outright scam or identity theft that could actually send the promised product with a product price that is less. If it arrives you will probably find there is a bill for customs duties that eat up the discount, as well as an absence of a U.S.A. warranty.
You might be able to get it for $100 less but that's doubtful. If B&H, one the most respected camera stores in the US has it for that price... that's the price.
