Under-construction properties hide too many costs.

Arekere / Bannerghatta Road fringes keeps coming up every time I shortlist something. I'm looking at a Prestige project there, under construction. What are the actual hidden costs beyond the quoted price? Stamp duty, registration, interiors, I know. But what else did you guys budget for? And for under-construction, how do you really assess delivery risk? Any red flags to watch for during site visits that builders don't usually point out? This is my first buy, so honestly, I'm quite lost. Any advice on what to specifically ask Prestige?