For a limited time, the Sigma 100-400mm f/5-6.3 DG OS HSM Contemporary lens is currently on sale ($100 off) for $699 at major US stores. The regular price is $799. This Sigma 100-400mm C lens is the most affordable 100-400mm lens on the market. Great deal, order now if you are interested.
Note: B&H is offering a free Sigma USB Dock and Sigma 67mm WR UV Filter with the purchase of Sigma 100-400mm C.
Sigma 100-400mm f/5-6.3 Contemporary Lens Store links: