Parsvnath in Asagarpur Jagir: Negotiation frustrations

Since January I'm shortlisting flats in Greater Noida, Parsvnath in Asagarpur Jagir. I'm in Dubai, can't visit. Builder quotes seem firm, but can we negotiate on a 3BHK for ₹1.5 Cr? Hidden charges ka kya scene hai? Last time, possession pe kaafi extra maang liya. Kitna realistically knock off kar sakte hain? Any experiences?