Hi, I think you may get this done between 1700 Rs/sqft - 1900 Rs/sqft. Though need to check the specifications I am not sure how many contractors you talked with. I feel you should talk to at least 3 contractor and provide them your exact specifications. Lets say Italian Marble (xyz rs/sqft), Sanita...

The construction cost for a decent quality construction from Rs 1550 -2000 Rs/sqft for Bangalore. But get the complete specifications and materials that the contractor will use for your project. It would be better if you can compare work by work - I mean excavation & foundation, RCC super structure,...