New Delhi flat cost is never just the sale price.

I'm looking at BMB Developers in Preet Vihar. Brochure price theek hai, but kitna budget for stamp duty, registration, interiors? Hidden costs bahut hote hain, suna hai. Site visit pe kya dekhoon jo builder nahi batayega? First-time buyer hoon, nervous. Any advice on what to really budget beyond the property price?