Amazon has another one of their short-term deals: the Sigma 135mm f/1.8 DG HSM Art lens for Nikon F-mount is now $1,097.11 or $301.89/22% off (currently out of stock, but you can still order it, ships from and sold by Amazon.com). Based on similar offers in the past, this deal will end in the next few hours. Other US retailers sell the lens for full price.
Additional information on the Sigma 135mm f/1.8 DG HSM Art lens can be found here.