What's the real total cost for a Gurugram 3BHK?

Did a site visit to Shree Vardhman's new project on Golf Course Extension Road last Saturday. Currently in a 2BHK in Sector 55, thinking of upgrading to a bigger 3BHK. The quoted price for a 3BHK was like ₹2.8 Cr, but then they started adding all these charges. PLC, floor rise premium... not sure if all that is worth it, yaar. My main confusion is around the *actual* total cost. Builder guys just talk about the base price. What about stamp duty and registration? Is that like 5-7% extra on the whole amount? Plus other hidden costs that pop up near possession, has anyone faced that with this builder or in this area? Trying to figure out the real ROI here. Also, for stamp duty, is there any room for negotiation or reduction on that part? Or is that fixed by the government? Just want to know what to expect and budget for properly, already have a home loan running.