Fair value of plot in Sreekaryam

Kind folks, We were interested in building a home in Trivandrum and wanted to find out what would be the fair value of a plot of land (*in per cent terms*) in a neighborhood like Sreekaryam. The prices quoted for the locality fluctuate a lot and I felt it would be getter to do some secondary research before approaching real estate agents or land owners. Are owners more amenable to negotiations when it comes to prices?