Logitech V200 Cordless Notebook Mouse (Silver) is £17.99 delivered from Play.com
This Precise optical-tracking technology 2.4 GHz (10m range) cordless optical mouse for notebook PCs has up to 1 year battery life and Tilt wheel plus zoom, that lets you scroll up/down, side-to-side, and zoom in/out. 3 years warranty too!
Probably the cheapest price for Logitech V200 Cordless Notebook Mouse. Checked some prices which include Pixmania (£23 + delivery), Big Pockets (£24.99 + delivery) and Savastore (£20.62 + delivery).