Delhi investors: What's your best negotiation trick?

My current 2BHK in Dwarka feels too small now, thinking of upgrading to a 3BHK or villa, maybe in Vasant Kunj or Greater Kailash. Budget around ₹3 crore. Already have a home loan, so trying to be smart with this next move. I'm looking at some projects by Reputed Builder and also some secondary market options. Honestly, price negotiation ka scene kya hai Dilli mein? Builders like DLF ya Godrej ke saath kitna realistically knock off kar sakte hain? Last time I bought, I felt like I left money on the table. And what about the all-in cost? Besides property price, stamp duty, registration, PLC, parking, interiors... are there always hidden charges jo possession ke time pe pop up karte hain? Especially in secondary market deals, can we negotiate more there compared to new projects? Kya lagta hai, where's the real value?