I would never spend any mad money on an Audi. They're so dull and soulless. S1 Quattro and S2 not withstanding.
Driven a fair few Audi's. They all have the same 'character'.
C63. Awesome sound. Wild drive. My friend has one.
A good very low mileage e46 M3 would be on my list.
Honda NSX for exclusivity. This thing is beautiful. High mileage but, it's a Honda. And one at the peak of their engineering capabilities at the time.
http://www.autotrader.co.uk/used-cars/honda/nsx/used-honda-nsx-hoddesdon-fpa-201603192130452?logcode=p
I might be tempted to consider a Corvette. A lot for your money. 7 litre V8!
http://www.autotrader.co.uk/classified/advert/201603312499258?onesearchad=used%2Cnearlynew%2Cnew&page=1&search-target=usedcars&radius=1500&postcode=ol138ax&sort=atcustom&model=corvette&make=chevrolet&logcode=p