This deal has ended.
Buy.com has the Xbox 360 Wireless Controller for $48.99 plus shipping is free and there is no sales tax (except CA, MA, MD, TN). New Google Checkout users can get them for $38.99 when they signup for and pay via that service. Of note: Amazon has these for $50 shipped. Most people are paying around $54 after tax at the local BestBuy.