Gurgaon builders always hide charges until possession

Our current 2BHK in Sector 50 feels too small now, and we're seriously looking at upgrading to a 3BHK or even a villa. We've seen some options, like in Flower Valley by Golden Housing Land Developers LLP. My main concern is the actual final price. Builder sales reps often say 'fixed price', but does price negotiation really work in Gurgaon? Kitna realistically kam ho sakta hai, especially for a 3BHK around ₹2-2.5 Cr? Also, I'm worried about hidden charges. Log bolte hain OC ke time par bahut extra costs aate hain, like for utilities or maintenance setup. Kya yeh sahi mein hota hai? Aur PLC ya floor-rise premium, is that extra paisa worth it? Ya phir just builder ka tareeka hai to charge more? Already stretching our budget.