Final 3BHK costs in Bengaluru: What's the real trap?

My wife's been pushing for a bigger 3BHK for the kids, and honestly, I'm dreading the final costs after seeing some initial quotes. Everyone glorifies the base price and stamp duty, but nobody properly explains the *real* hidden charges that pop up just before possession. I'm looking at a Prestige Group project near Deepanjali Nagar, and their cost sheet is so vague on these. Is it just me, or do builders intentionally hide things like absurd maintenance deposits, utility connection fees, or even 'amenity upgrade' charges until the very last minute? What's a realistic 'all-in' cost for a ₹1.5 Cr 3BHK in Bengaluru once all these extras are piled on? I don't want any surprises when kids' school admission is just around the corner, especially after paying PLC for a higher floor. Change my mind, but I think it's a deliberate trap. Disagree? Tell me your experiences.