My Noida Extension total cost reality check

The listed price in Noida Extension is just the starting point, not the total investment. I'm in Dubai, eyeing Sector 71 for a 3BHK around ₹90L. Can't visit, so need ground truth. Divyam Group projects mein all-in cost kitna aata hai? Beyond PLC/parking, what hidden charges like stamp duty, registration, etc. should I factor? Construction-linked payment better for an investor, ya down payment? And where are the real price correction zones for value buys, avoiding hyped areas? Legal clarity needed too.