First-time buyer confusion: total cost and site checks

Last 6 months se Noida Extension mein flat dekh raha hoon, Salarpur Khadar side. Town Park Buildcon ke projects bhi dekhe hain. Property price ke upar kitna extra budget rakhna chahiye? Matlab, stamp duty, registration, interiors ka idea nahi lag raha. Aur site visit pe kya kya check karna important hai jo builder nahi batayega? Honestly, first-time buyer hoon, badi confusion hai.