Downsizing to Deenpur: My all-in cost shocker

My kids have finally moved out and our big GK house feels so empty. We're planning to sell it and downsize to a compact 2BHK or small 3BHK, something manageable with an elevator, near a good hospital. Budget is around ₹1.8-2.2 Cr. I visited a Sk Builders And Developers project in Deenpur. Base flat price toh theek laga, but the 'all-in' cost calculations are confusing me. Builder ne sirf super area ka rate bataya. Stamp duty, registration, PLC, parking, yeh sab mila ke kitna extra jaata hai? Aur negotiation ka kya scene hai New Delhi mein? Can one realistically expect 5-10% off the quoted price, ya fir woh bas marketing tactic hota hai? Don't want any hidden charges popping up at possession. Has anyone dealt with Sk Builders, ya fir Deenpur area mein, and faced unexpected costs?