Negotiation on new properties in Delhi is a myth, change my mind.

I'm convinced negotiation barely works for new properties in Delhi. Builder bolte hain 'fixed price' and don't budge much. For a 3BHK in Dwarka, say ₹2 Cr, kitna realistic discount mil sakta hai? Also, construction-linked plans versus full down payment, investor perspective se kya better hai? Shiv N Sai Builders ke hidden charges ka bhi darr hai, possession pe kitna extra maangte hain log?