Upload & Sell: Off
According to canonpricewatch (http://www.canonpricewatch.com/product/03868/Canon-EOS-5D-Mark-III-price.html),
All 3 of B&H, Adorama, Amazon have it for $2990 (minus 2% rewards, so $2930)
Profeel (auth dealer) through eBay has it for $2979 (minus 2% ebay cash, so $2919)
BuyDig has it for $2975
eBay is the cheapest if you regularly use it, then B&H or Adorama or Amazon if you can use the rewards in January, and finally BuyDig has the lowest price. Phew, that's complicated!