Dwarka 3BHK possession mein hidden costs ka kya scene hai?

The final cost of a 3BHK in Delhi is never just the stated price. My Dwarka flat's possession last month had ₹2-3 lakh extra for 'maintenance setup' and 'utility connections' not mentioned earlier. Is this normal? For investors, is construction-linked payment smarter than a lump sum down payment for ROI?