The sale has been extended for the Sigma 150-600mm f/5-6.3 DG OS HSM sport lens. The sale was originally to end yesterday, but has since been extended to January 31st. So if you were thinking about buying this lens but missed the sale, you are in luck! But make sure to do so before the end of January.
You can buy the lens from B&H Photo for Canon, Nikon, and Sigma.