Though its a delayed reply, it may help!
We have paid 2 year back Rs. 260 for 4 in x 6 in and 8 ft height stone from Krishnagiri. The local installing person managed to get the stones. 280 Rs could be the current price if the stone quality is good for 8 ft height. When you bargain, you will get varying thickness.
Labor seems costly, we paid close to 140 for installation and whitening the stone. Labor may vary depends on the area. My person was not getting much profits as he pays his team high.