SoftUK are selling "Boogie" for the Nintendo DS for £10.99 & "Boogie" (With Mics) for the Nintendo Wii for £24.39..
Use the code "Cheap Games" (without quotes) to get free delivery.
You can get cashback via some sites (e.g. 2% Free Fivers). You can also get 6% cashback through SoftUK's 'Collector' program
The next best price for the DS version is £13.99 (Woolworths) and £26.99 (PowerPlay Direct) for the Wii version..
PLEASE NOTE: SoftUK has recently had periods of time when the site has been down, so if you can't get it to load, try again later. :-)