Upgrading for kids, but costs are a shocker

Honestly, I thought buying a 3BHK for my kids in Sohna would be simpler. We're eyeing a place near Sohna Road, maybe Pyramid Infratech. Budget tha ₹1.8 Cr for a decent 3BHK. But ab pata chal raha hai, stamp duty, registration, phir PLC, parking, yeh sab milake budget kitna badh jaata hai! Builder ne pehle theek se bataya hi nahi. Is it normal for these extra costs to add 10-15%? My wife is worried about school admissions if we stretch too much. How do you guys factor this all-in cost?