Cossies always need something, service parts for a sapph are no more expensive than any other car, it's when you start upgrading things that the list becomes endless.
If you found a lightly modified stage 1 car and we're happy to keep it that way the costs would be minimal unless you ragged it about.
Frs is still 12/13 years old now and like any car of the same age it will cost something to keep it in good running order.
Both great cars but no other car I've driven comes on boost like a cossie.