Hidden costs buyers only discover after possession in Greater Noida

The 'final cost' builders show you is never the real deal, especially in Greater Noida. I work in real estate, but buying my own 3BHK near Sector 150 is a totally different ball game. I'm checking out Godrej and ATS, but yaar, inki sales team initially PLC, IDC ke poore numbers nahi batati. Lagta hai possession ke time pe hi hidden charges dikhenge. Also, construction quality ka kya scene hai? Suna hai ACE Group ke projects mein plaster cracks aur seepage issues aate hain. Mahagun aur Gaursons ke baare mein kya views hain? Is their finishing actually good ya sirf marketing hai? Kaunsa builder sahi mein quality deliver karta hai? Have you guys faced unexpected costs at possession with any of these?