Top Rated Plus eBay seller and authorised Sigma dealer CameraLand (99.8% positive ratings) has the awesome Sigma 50mm f/1.4 DG HSM Art lens on sale for $739.99. Compare at $849. Free shipping in the US. This is not a grey import, CameraLand says:
As one of the largest Sigma dealers in the USA we are happy to offer this great lens at a super price. It comes with the USA Warranty.
We had an in store demo and these were shown and put back in the box. Because of this we won’t sell them as new never opened