B&H has the Sigma 150-600mm f/5-6.3 DG OS HSM lens for $1799 (reg. $1999) through January 31, 2015. You also get 10% rewards on the lens, which adds up to about $180 credit at B&H. The lens is available in Canon, Nikon and Sigma lens mounts. Check it out while it lasts here at B&H Photo.