Falken F452s seem to be generally recommended on this forum as a competitively-priced performance tyre (non-runflat), I think if you search 'Falken' you should get some more detailed analysis!
Run flats can be bought from anywhere. Not sure which wheels you have, but 18" rears will cost up to £280 each at Kwik Fit, but as low as less than £200 from some mobile fitters. I'm probably in the minority here, but I'm sticking with the standard issue tyres on mine despite the higher cost and apparent ride harshness.
Nice tire, but not to be compared with a ps2 etc
I can really recommened the Michelin PS2 (now for 3 days and allready great, way better than the Continentals..)