This deal has ended.
Buy.com has the best deal this year on an Xbox 360 Wireless Controller: just $36.25 plus shipping is free and there is no sales tax (except CA, MA, MD, TN). This is almost $2 below the $37.98 low it hit last month. Most people are paying around $54 after tax at the local BestBuy. Also of note: Buy.com has a new and very-rare $5 off $50 coupon valid in all stores for new customers through 3/31 and new Google Checkout users can get a $10 off discount for signing up (but you can't get both).