Weighing Air Force School in Begumpet for my 9 year old and trying to budget properly

We are considering it for the coming year. Before we apply I would like a realistic annual number, not only the tuition figure. In my experience the extras are where the estimate goes wrong: transport, two sets of uniform plus sports kit, books, clubs, trips, the occasional event contribution. My question is about process rather than this particular school. When you were applying somewhere, did you build the estimate from what the school gave you, or from what other parents actually spent? I suspect the second is more accurate, but I have not tested that assumption, and I am not sure how to ask parents without it feeling intrusive. It is past one and I should be asleep, so apologies if this is rambling.