I use this website as much as possible for computing purchases as i'm sure alot of others here do!!
Just realised they have a forum and you can post in a section of it if you find something cheaper elsewhere and they will try their best to beat it! They can't always do this but if they can you get your game cheaper from a great company and free recorded delivery so no problems with things going missing!
From the site
Ok, so taking Customer Services one step further, We here at ShopTo are encouraging you to point out other online retailers who are selling the same products as us, cheaper than us!
PLEASE NOTE: ShopTo can't normally match the tax-free retailers who ship from Jersey/Guernsey (Play, Sendit, Amazon Jersey, Woolworths Jersey, HMV, Tesco, all have divisions that mail from the Channel Islands), please check before posting.
For example, i'll start off:
PC Game Ancient Wars Sparta,
£24.99 at http://www.shopto.net/page.php?page=det
£17.98 at Amazon.co.uk
Now, ShopTo will look at their price and if they can lower it/match the price, they will. This isn't a given, sometimes they wont be able to, but they wont try if they aren't alerted to it, so make use of this sub-forum to drive down prices even further!