New Delhi property: What's the real negotiation margin?

2.5% negotiation on property prices in New Delhi – is that realistic for an investor? I'm based in Dubai, so ground reality check mushkil hai. Builders like Anil Suri Group, kya woh log actual mein negotiate karte hain for a 3BHK in Saket or Vasant Kunj? What's the real discount one can expect? Also, construction-linked payment plans better hain ya down payment for maximising deal value? What hidden charges, like PLC or OC, should I look out for? Can't do site inspections easily, so need to factor everything in for ROI and total cost of acquisition.