What nobody tells you about Noida property negotiation

Been looking for 8 months now and it's getting exhausting. Fed up of renting, finally decided to take the plunge and buy a flat in Noida. I'm eyeing some 3BHKs in Sector 150, around ₹1.5 Cr range. Builder hai UTC Constructions. Yaar, inki quoted price pe kitna discount expect kar sakte hain? Sales guys bolte hain 'fixed price' but I've heard negotiation chalta hai. It's frustrating when they act like it's non-negotiable. Also, all-in cost mein kitna extra laga dete hain? I'm worried about hidden charges like maintenance deposit, club membership, ya phir last-minute PLC adjustments. Is there a way to factor these in beforehand ya they just spring them on you at possession? Koi actual experience share karo please, especially for under-construction projects near Jewar. Realistically, kitna negotiate kar paaye ho? And what are the biggest hidden costs to watch out for?