Pre-launch discounts are often misleading

Not proud of this but I almost got duped by a pre-launch scheme. Varthur mein Keya Homes ke ek project mein, initial quote ₹1.5 Cr for a 2BHK tha. But jab full breakdown dekha, it was shocking. Builders usually quote just the base price, right? Phir aata hai PLC, floor rise, parking, club membership, electricity meter charges… the list goes on. These add up significantly. I've seen them push the final cost by 15-20% easily. Kya aapne bhi experience kiya hai ki possession ke time par naye charges nikal aate hain, like maintenance advance for 2 years or corpus fund? Yeh sab total ROI ko affect karta hai. Pre-launch mein jo discount dikhate hain, woh often in hidden costs se offset ho jaate hain. How do you guys factor these in your calculations? Is there a thumb rule for these 'surprise' expenses in Bengaluru?