It may be calculating the shipping costs to your zip code if you're logged in. The best thing to do is call Abt and see if they'll honor that price.
I have been tracking the pricing on the LN37B650 since it was announced. The cheapest that I have seen is just under $1000 delivered. Today, CNet shows Abt Electronics selling it for $849.99 but when you click the link, Abt.com shows the price as $1099. Is there any chance that the $849.99 price is for real?