Looks a good light for the money - gets excellent reviews. This is the cheapest i can find it and its £21.99 at Chain Reaction (excellent reviews there too).
Choose "2 new from £15.99" and choose amazon free super saver delivery.
Here is the correct link for £15.99 with free delivery, I can't change the main link:http://www.amazon.co.uk/gp/offer-listing/B000NOO3SS/ref=dp_olp_new?ie=UTF8&condition=new
* Nine super-bright white LEDs for great visibility
* Focused lens and reflector technology offers a concentrated beam of light
* Push-button waterproof switch, easy to operate even with winter gloves
* 2 modes, flashing and constant
* CNC aluminium construction
* Great runtime to power ratio - up to 70 hours
* Robust, water proof design, perfect for those wet winter nights
* Handlebar mounted quick release bracket (included) for everyday convenience
* Requires 4 x AAA batteries (included)