By this you mean the Mugen M200?
Its nothing more than a Championship White edition FN2 Type R with a Mugen plaque, black wing mirrors, mugen front/rear bumpers, and different wheels, apart from this there are no other differences from the Mugen M200 version and the 'normal' FN2 models. So the parts and service prices are the same...its more a badge engineering and cosmetic excercise really, it has no Mugen performance or 'mechanical' parts.
If you mean the ultra rare Mugen M20 version though (the one that cost nearly £40k when released, and they are very very rare cars, so I doubt you will be looking at these), then that has some quite considerable differences that would likely impact upon costs (for example, it has 4 pot brakes with Mugen pads and different disks from the more regular FN2...these cost a lot lot more).