You must be joking about the "supercar" part I hope.
The renault clio RS isn't exactly fast, I would class it as nippy, it merely feels fast because it's essentially a cardboard box on wheels.
Brand new, I would class it as poor value for money. I would pay a few k for one, I would never pay £15,000 for one as they are poorly engineered and IMO not worth £15k, even when new.
If it must be a hot hatch, something like this
http://search.autotrader.co.uk/es-u...cleYearOfManufacture=2007&vehicleRegLetter=57 will be better value for money as it's a little older, but will have some money spent on the interior and engineering of various mission critical parts.