My Rajkot 3BHK hunt: The hidden costs are scaring me

Since January I've been shortlisting flats in this city. Currently I'm in a 2BHK near University Road, but family badh rahi hai, so thinking of upgrading to a 3BHK ya small villa around Kalawad Road or 150 Feet Ring Road. My budget is roughly ₹80L to ₹1.2Cr. Builders like Galaxy Group ke projects dekh raha hoon. My main confusion hai about the true 'all-in cost'. Builders initially quote one price, but then stamp duty, registration, PLC, parking, floor rise, GST... it all adds up. Is there a thumb rule for how much extra one should factor in over the base price in Rajkot? Is it realistic to expect a 5-10% discount on the listed price from builders like Galaxy Group in areas like Mota Mava? Or should I just focus on getting all costs upfront? Any specific charges that only appear during possession time in Rajkot, jo I should be aware of? Already have a home loan so don't want any surprises.