My 2BHK upgrade dream: Greater Noida's real cost?

My 2BHK in Sector 78 is getting cramped, so I'm seriously looking at upgrading to a 3BHK in Greater Noida, maybe near Phi II. Budget ₹1.2-1.5Cr. Builders like One Leaf Group mein dekha hai. Yaar, price negotiation kitna possible hai? Is it worth trying to knock off anything substantial, ya builders won't budge? Also, all-in cost ka kya scene hai? Basic price ke alawa stamp duty, registration, parking, PLC... kitna extra charge ho jaata hai? Don't want hidden surprises at possession. What's your experience with these extra costs? Should I push harder for discounts?