Check down the right for Amazon as the seller (or click on "26 new from £XX.XX").
This is the cheapest I've found online by a reputable retailer for the Remote Plus (with in built motion plus, which is miles better than the attachment). Was £30 on Amazon only yesterday, so a 10% discount has been applied for whatever reason! £35-40 most other places.
The Wii Remote Plus, is an updated Wii Remote with built-in Wii MotionPlus hardware, which gives players an incredible level of precision and gameplay accuracy without the need of additional add-ons.
Available in four colours - white, black, pink and blue, the Wii Remote Plus has the same physical dimensions of the standard Wii Remote and all compatible peripherals can be plugged into the base of the Wii Remote Plus as before, such as the Nunchuk or Classic Controller.
Functioning in exactly the same way as the Wii Remote with Wii Motion Plus connected together, the Wii Remote Plus enables players to see every twist of the wrist or arm, brought to life and faithfully replicated on the TV screen with the use of one, compact controller.
Players of games such Wii Sports Resort and FlingSmash will be able to take full advantage of the enhanced accuracy and realistic motion control which the Wii Remote Plus offers, as every swing of a golf club or fling of Zip is reflected in real time on screen.