After seeing very low prices for a Canon EOS 5D I called three sites trying to place an order. 2 of them, Royal Camera and CCI immediately aknowledged the camera advertised was actually a gray market item and not intended for sale in the USA. I doubt they would have been forthcoming with this information had I not asked. What does not make sense is that on both sites the camera came with a $300 manufacturers rebate. Since the cameras were not intended for sale in the USA, there is no way Canon will give this rebate.
The third company I called, USA Photo Nation, confirmed with me that they were selling a USA market camera. They confirmed another group of concerns so I decided to make the purchase. Only after getting my credit card information did he go into hard upsell mode. I expected since and simply said no thanks to all of it. He told me the battery only lasts 30 minutes, which is a lie, and I told him that is fine. He then told me the camera I ordered comes with a polycarbonate body and if I would like the magnesium alloy body that will cost more. I told him the 5D does not come with a polycarbonate body either in the USA or anywhere else. After arguing he accused me of being a reseller, which I am not although I don't know why that matters.
Bottom line is these sites are all scams and not even very good ones. Unfortunately, Canon, Nikon and other manufacuters have no responsibility here which leaves it to buyer beware. If the deal appears to be too good to be true, it most definitely is.