Home loan ke saath upgrade: New Delhi mein sahi deal kaise mile?

Under-construction properties ka risk mujhe thoda zyada lagta hai, honestly. 2BHK se upgrade kar raha hoon. New Delhi mein Sapna Ghar Apartment aur Tony KP Builder Floors dekh raha. Tony KP toh completed hai. Sapna Ghar ka status 'null' matlab kya under-construction? Builder trust factor kaisa hai? Total cost of ownership mein kitna farak padega? Already home loan hai, so budget tight hai.