Look up cost of deferred maintenance that comes with those cars.
When it comes to those you want to buy the nicest one you can afford. Look up fellow named Matt Ross on YT, he is fixing up a basket case 996 Turbo, an endless money pit.
They're NOTHING compared to a Ferrari or Lambo in terms of maintenance though. As long as you don't have bore scoring or the IMS gone (IMS isn't an issue on the Turbo motors luckily), the rest of it is all pretty run of the mill. I'd take a 996 long before I'd take a F355 or F360.