I don’t reckon it would cost much at all. There are staff rostered on who are already being paid. If a SARTIME is not cancelled, they pick up the phone, speak to the pilot, get a cancellation, say thanks and hang up. You don’t pay them extra for doing their job.
It’s like a shop. No customers but staff are still being paid. You don’t pay them extra when they serve a customer.
9000 per year is 25 a day, about one per hour, hardly a burden. You have to stop tilting at windmills.