Is the 'all-in' cost always so much higher?

My kids' school admission is next year, and I'm totally stuck on getting a 3BHK in Bengaluru. We checked out Sanjeevini Properties near Kachamaranahalli. The base price for a 3BHK was around ₹1.3 Cr, but the 'all-in' cost felt like a bait-and-switch. They added PLC, floor rise for the 4th floor, parking, then stamp duty, registration, and even some unexpected maintenance deposits. It's frustrating when the final number is almost 20% higher than what you initially budget for. How do you guys get a clear, true all-in cost upfront from builders? My wife's priority is a safe area for the children, but honestly, this keeps blowing our budget. Is this just how it works here?