They could do the parts cheaper but once they're 3 years old and out of the dealer network they don't care , it's not about scale of production, the cost of forum brake discs v maserati prices tells you that ,the components to build a car are costed to arrive at a profitable retail price so any produced as spares have already had the development costs recouped in the sale of the new cars.
If they weren't ripping customers off parts would be the same price whether they were in a fiat, Alfa or maserati box
And don't get me started on the ridiculous prices for service work , I'll be picking up a 5.0 mustang sometime in the next week or so , if I buy the service plan it's £600 inc vat for 3 years servicing inc AA cover
What's the service cost on a v8 maserati over the same period 4x 5x 6x
The 25,000 mile service cost on a diesel ghibli is over £1000 , I've had diesel cars for decades , service is oil, oil filter, fuel filter, air filter, pollen filter then go round checking things where on earth they get that number from I have no idea