First-time buyers: What hidden costs surprised you most?

Visited a few properties in Rajpur Khurd Village last weekend, including a Sonu Lamba project. Honestly, it's so much more complicated than I thought. Broker ne toh sirf property price bataya, but stamp duty, registration, legal fees, interiors, electricity connection... yeh sab mila ke meri budget hil gayi hai. I liked a 2BHK there, but the total cost is way higher than expected. Koi batata hi nahi ki OC kab aayega ya initial booking ke baad itne hidden costs hote hain, I had no idea. It feels like nobody tells first-time buyers these things until it's too late. Has anyone else faced this sudden jump in costs? Kya ye sab negotiable hota hai ya mostly fixed? What's a realistic percentage to add for these extra costs beyond the actual property price? Ab samajh nahi aa raha kaise budget karoon.