Can't trust the quoted price in Gurgaon, need advice

₹1.5 crore for a 3BHK in Sector 53 feels like a lot, especially after selling our Delhi home. Kids have moved out, so my wife and I just want something manageable, maybe 2BHK, with an elevator and low maintenance. We saw a Keystone World project, looks decent. But I'm honestly not sure about the *true* all-in cost. Builders quote one price, par phir stamp duty, registration, PLC, parking, electricity meter... sab add up ho jaata hai, isn't it? What hidden charges should we really watch out for, especially near possession? Also, Gurgaon mein negotiation ka kitna scope hai? Ya mostly "take it or leave it" market hai? Kitna discount expect kar sakte hain?