Gurgaon property: The real all-in cost nobody discusses?

After years of renting, I'm finally taking the plunge and looking at property in Gurgaon. Fed up of paying rent, landlord ne phir badha diya. I'm checking out Sector 82A, maybe Pyramid Infratech projects. Builder bol raha hai no negotiation, but is that true? Kitna discount realistically milta hai ya spot discount pe kitna expect kar sakte hain? Also, all-in cost ka kya scene hai? Base price ke upar stamp duty, registration, PLC, parking, yeh sab toh pata hai, but aur kya hidden charges hote hain jo possession ke time pe aate hain? Maintenance advance, electricity connection, society formation fees? Kya kya dekhna chahiye to avoid surprises later?