NRI Builders mein price negotiation kitna hota hai?

Kitna negotiation possible hai actual mein Gurgaon mein? NRI Builders ke projects mein, especially U Block mein, kya price kam kar sakte hain? I'm looking at a 3BHK around ₹1.5 Cr, maybe on SPR. Log bolte hain builders fix price rakhte hain, but I'm worried about hidden charges jo baad mein aate hain. Like OC ya maintenance deposit. Koi bata sakta hai kya ispe kitna effect padta hai total cost pe? Ya koi first-hand experience?