Gurgaon resale flat: Stamp duty calculation confusing for investors

Gurgaon mein resale flat ki stamp duty calculation pe anyone has clarity? I'm eyeing a 3BHK in Sector 82, M3M Urbana. Broker keh raha hai stamp duty original agreement value pe lagti hai, current market value par nahi. Is this sahi? Ya fir it's on current circle rate? For an investor, this heavily impacts total acquisition cost and ROI calculations. Any smart ways to manage registration charges, ya fir it's just fixed? Hope someone has a trick.