This is the cheapest I have found for Intel's latest and greatest S1150 mainstream performance processor. The 4790K is a newer, faster and more overclockable version of Intel's 4770K.
Price is listed as £239.98 but use code "HEAT10" to bring it down to £229.98.
It's obviously not for those who want to build a budget PC but for anyone looking high-end nothing can touch it for the price.
edit: Plus claim 3x free games and 1-years fully licensed McAfee LiveSafe.