B&H discounts certain items for attendees of various photo shows. These are given a special code which you enter in the search box on their website to obtain that price. Since there is no code for the 400 5.6, the price is $1099 as shown on their site.
another option would be to try and get it to show up in your recommendations in amazon, gives 5% off. I've actually had the 400 2.8 show up a couple times there.
