Shalimar Bagh: The true cost of downsizing

Shalimar Bagh keeps coming up every time I shortlist something. Our kids have moved out, so we're looking to sell our big house and downsize to a manageable 2BHK or compact 3BHK. Saw a Shree Radhey Builders project, also some resales. The base prices around ₹1.8-2.2 Cr for a 2BHK seem okay, but I'm worried about the *actual* all-in cost. Honestly, how much should one factor for stamp duty and registration in Delhi? I'm seeing figures like 6-7% on top, which is a huge chunk. And what about other hidden charges? Brokers are always pushing for quick decisions, but I don't trust them to be fully transparent about everything beyond the quoted price. Are there any specific things to watch out for that only pop up later? Trying to avoid nasty surprises. Any negotiation tips for these extra costs, or is it just the property price that's flexible?