And as Simon has alluded there is a great series 4 car (10k miles) coming on the market very soon at a price certainly starting with a 5 however nearer £60k than £50k if you're interested?
Would have to be an exceptional car with perfect history for me to consider upping budget for a 4, but never say never. Taking onboard the good advice from all so far, I'll be buying on condition rather than year / miles.
Very similar to Caterham world
Dave.