Noida Extension 3BHK: What's the *actual* final cost?

My kids' school admission is next year and we desperately need a bigger 3BHK in Noida Extension. Om Infra ke projects dekh raha hoon Sector 9 mein, but I'm worried about the true 'all-in' cost. Builder price ke alawa, what else is there? Stamp duty, registration, PLC... kitna extra lag jaata hai total? Mera budget ₹1.2 Cr tak hai. Aur possession ke time kya hidden charges aate hain? Maintenance ya koi aur unexpected costs? Wife ka priority hai ki neighbourhood safe ho aur koi financial surprises na hon. Koi experience share kar sakta hai?