Has just dropped in price from £12.99... Amazon prices seem to fluctuate so will probably go back up soon.
Have also put my £2.50 voucher to good use... :) - Making it £7.49 for an Official Wii Nunchuk
Contoured to perfectly fit a player's hand, the Nunchuk builds on the simplicity of the Wii Remote and goes an extra step to meet the needs of gamers. The Nunchuk connects to the Wii Remote at its expansion port and is used in conjunction with the Wii Remote.The Nunchuk contains the same motion-sensing technology enabled in the Wii Remote but also includes an analog stick to assist in character movement. In several games, players will use the analog stick of the Nunchuk to move their characters and the Wii Remote to perform a specific action, whether that's throwing a pass in football or aiming a ranged weapon in an action game.Along with the analog stick, the motion-sensing Nunchuk also contains two buttons positioned for quick access. Because the Wii Remote and Nunchuk are only relatively dependent on each other, players are free to hold them in whichever hand is most comfortable. The ambidextrous nature of the Wii controllers grants accessibility seldom seen in game controllers.
Wii Nunchuk Black Nintendo : WII