Beyond property price: Noida's hidden costs

What unexpected costs hit you after booking your first flat in Noida? I'm looking at SS Buildcon in Sunpura and honestly thought I had my budget sorted. But then stamp duty, registration, and now interiors... it's all adding up so fast. My parents keep saying there's always more to pay. What else should I factor in, beyond the property price? Is there a rough percentage for these extra expenses? Not sure if I'm missing something big.