My N/A racks up at least 300 miles a week and has been used every day for the last 6 years. I don't take much notice of running costs anymore; I can afford to run it, so I run it.
I use at least a tank of fuel (60 litres) a week (280-360 miles depending on mood),
A set of tyres a year at £5-600. Then there's brake pads, oil filters, plugs, general servicing; probably looking at £1000-£1500 a year (at a guess) plus tax, MOT & insurance.
Due to age, it's recently had a full set of new brake calipers, rear wishbones, linkages, etc and is due to have the front links done this year, probably totalling around 3 grand for all that lot. Definately worth doing, it drives & handles a lot smoother now (and passes MOT's)
These are old cars now, so you need to factor in things like that or find one that's already been done. Once they're done, they'll probably be good for another 15 years or so.