Gurugram super area calculations are just misleading.

₹7500 per sqft for super area in Sector 7 feels like a rip-off. Builders like Model Economic Township quote super area, but carpet area toh bohot kam ho jaata hai. I'm seeing a 30% difference sometimes. Is this normal? Matlab, itna difference kyun aata hai? Also, legal verification mein kya kya check karna chahiye? RERA website pe details dekh li hain, but title search aur encumbrance certificate ke liye kahan jaana padta hai? Builder toh bol raha sab clean hai, but I don't want to take chances.