Someone might know someone who knows someone, but all I can say is, good luck getting what you want for only £200. I think you might be bing a tad ambitious. You may need to increase your budget, or lower your expectations - particularly for a viable gaming machine at that price, for current games (as opposed to older, less graphic/processor intensive games).
-------------------- TFC 'Going to trial with a lawyer who considers your whole life-style a Crime in Progress is not a happy prospect.' - Hunter S Thompson (1937-2005)