I have to be honest here - I've had it 5 years. It never sees a specialist, just gets an oil change every year, lives on my drive, and gets thrashed on track days a few times a year.
In 5 years, outside of tyres, brakes and oil, all it has cost me is 2 keys (although this was £300) and an alternator (under £200 incl. fitting).
I may have to splurge £2-£2.5k on getting it back to how it should be. But it's at least holding value, if not appreciating, as it's a non-turbo flat-6.
I sometimes think I should have bought a Barchetta, Alfa GTV or Honda S2000 - but none of those allow you to tell people you have a Porsche. And none have a flat 6 wailing away behind your shoulders.