On the contrary, I've spent approximately $0 'fixing' mine. Just the usual maintenance stuff, even daily drove it (standard engine + turbos).
As long as GT-R is standard and maintained properly, it'll run. But they are not a good daily driver (expensive to run). GTS-t would be better suited (my R32 GTS-t was an awesome daily, with R34 turbo it did 9L/100km).
Of course, as soon as you start wanting more power, costs blow out massively on the GT-R.