What I didn't expect about payment plans in Noida Extension

Budget finalized for a 3BHK upgrade, already have a home loan for my current 2BHK. I'm looking at Blessings Homz in Sector 22 Yamuna Expressway. Builder is pushing Construction Linked Payment Plans, bolte hain easy hota hai. But pre-launch mein price kam mila hota toh shayad down payment plan better rehta? Not sure kitna fark padta hai final cost pe. Plus, super area aur carpet area ka difference bhi samajh nahi aa raha. Builders inflate karte hain kya numbers? Koi experience share kar sakta hai ispe?