What's the real negotiation room for a 2BHK in Noida?

Does price negotiation actually work for 2BHKs in Noida, or is it mostly fixed? My kids have moved out, so we're selling our big house and looking for something manageable, maybe in Natthu Colony or Sector 137. Brys Group has some interesting options around ₹90L. I'm trying to figure out the actual all-in cost. How much can you realistically knock off the listed price, like 5-10%? And what hidden charges should I really watch out for near possession? Don't want any nasty surprises after selling our existing property.