My guess is that the best deal is probably not advertised. Get the information together on what you want and call Larry at Mountain High Cyclery, Chad at Red Barn Bicycles or Jared at Downshift Cycles. Experience has shown that this is where you'll probably find a great deal and excellent customer service.
'If Wal-Mart sold parachutes, who would jump?' Frank Havnoonian (quoting his father) Drexel Hill Cyclery
Checkout pricepoint.com. They have some 2006 xo left over for good prices. Last week I picked up an xo rear der. for like $150 and xo trigger shifters for under $200. I don't remember the exact price but they seemed like decent prices.