First-time buyer in Sector 49: What did you actually pay beyond the flat price?

₹78 lakh for a 2BHK in Sector 49 seemed okay initially, but now I'm seeing so many other costs. I'm looking at Bricksquare Developers and honestly, I had no idea how much stamp duty, registration, and interiors would add up to. My parents keep saying there are so many hidden costs beyond the flat price, and they're right. The builder agreement is also super dense. Are there common red flags I should really watch out for? What did you guys budget for all these extras? Am I missing anything huge?