I bought one earlier today, just keep an eye on the used car dealership.
The car still has totally inaccurate geaging as in gt4, put a fully customiseable racing gearbox in and its pretty much spot on factory spec. A friend of mine has his 'blade' up for sale at the moment and I have followed and led this car on the road in my seven on several occasions and also feel that the modelled performance is probably out by 20% in a straigh line to the real thing ( which barely out drags a warm hatch in game). /rant.
If you are looking for realism then add the softest sport tyres as these cars (I think only about 20 were made, and only 7 factory blackbirds, tech bod point here, the fireblades were actually built under license by James Whiting) were all as standard on Avon ACB10 tyres, the formula ford single seater tread moulded crossply slick which is only just road legal in the uk.
As for setup if the tyres are correct for physics the sport tyres are Yokohama A048 radials which should require 1 ish degrees of camber at front 0.5 at the rear (quite difficult as the ' blade' is infact live axel at the rear not dedion as most modern Caterhams). Front camber on crossplys i.e. slicks should be circa 3 degrees.
If you want further info on track setup for caterhams look at www.blatchat.com - techtalk.
It's a great car for the "British lightweight" event, great fun on london track, and can net you some good credits.
The car also accepts a lot of extra power if you want, I took it to 198bhp, and its still very controllable, though I preferred it with less power ... It's just so fun, has so much spirit, yet when it goes, it's pretty straightforward to use opposite lock to bring it back.