Hidden costs buyers only discover after possession

The actual cost of my 3BHK on SPR was way more than I expected. Just got possession last month near Sector 79, and man, the 'hidden' charges hit hard. My builder, M3M, quoted ₹1.8 Cr for the flat itself, but with stamp duty, registration, and all those random utilities fees post-OC, it jumped another ~10-12%. Honestly not sure if any negotiation even works these days. Tried to push for a spot discount but barely got anything significant. Is this normal? Did anyone manage to negotiate substantial price drops on their property in Gurgaon, especially for a new flat? Or is it just a take-it-or-leave-it market now? Feeling like I should've dug deeper into the all-in cost earlier.