Noida property: What's the real negotiation room?

Construction-linked payment plans are often oversold as the safer option, but they hide significant interest costs over time. I'm looking at a Vivacity Creators project in Sector 158, and the upfront discount for down payment plans seems more appealing on paper. Does anyone have experience negotiating better terms or an actual spot discount beyond the stated offers? For a 3BHK around ₹1.8 Cr, what's a realistic negotiation margin in Noida right now? I'm thinking 5-7%... is that too aggressive? Also, what hidden charges should I really watch out for beyond stamp duty and registration? Things like extra PLC, club membership, or even maintenance advances at possession that aren't clear initially. From my experience, these add up quickly. Any specific 'gotchas' in Noida that people often miss? Hope this helps someone else too.