[Giller]

So many variables....and luck - who can say what it will cost. There are so many hidden gremlins that even a good PPI can't see, like IMS for example.
And when you say running costs - what are you including? Insurance and gas or just fix-it stuff?
If you went out and bought a decent, new car, you would have a monthly payment in the $350ish range or so. If you can spend less than that on a high performance sports car like this, that's a pretty good deal I would say.
Budget $200/month - and if you don't need it, you've got a little pot of money for retirement or what-not.