All-in property cost in Gurgaon is never what they quote initially.

All-in property cost in Gurgaon is never what they quote initially. We're looking at a 2BHK in Sector 89-90, kids have moved out so don't need such a big place anymore, just something manageable with an elevator. Builder jaise AS Estate waale will quote a base price, but then they add stamp duty, registration, PLC, parking, phir interiors ka alag se. Matlab, kitna extra lag jaata hai? For a ₹1.5 Cr flat, I'm trying to figure out the actual total cost. Is it usually 20-25% more? And construction-linked payment plans, are they really better than a straight down payment for someone like us selling an existing property? Doesn't that just drag out the financial commitment? I'm worried about hidden charges near possession too, like society maintenance fund ya water connection charges jo pehle clear nahi karte. Anyone have experience with this, especially in new projects? Kya humein koi legal expert se check karwana chahiye, ya brokers are usually transparent enough? Really want to avoid any nasty surprises.