This post is for UK runners. What a website ShopWiki.co.uk is indeed! Check their page for running shoes. You will be delighted by the offers. Contrary to the other shops online, the website does not take merchants on commission basis.
As a buyer, the first advantage for you is that you have manifold number of options to choose from as the number of merchants participating in the offer is virtually limitless. The second advantage, we may say more important than the first one probably, is that the result shown is non-biased as the website doesn't judge any merchant based on the commission structure, but only in a generic way as a search engine — Google.
There are many other advantages, not only for UK runners, but for others who are interested in any type of running, Pedometers, sports nutrition, etc. You much check all these; really useful pages on the internet.
Note: The image above has been taken from this flickr page of Timothy Takemoto under creative commons license.