it is coming to my notice that the per sq. ft .(super built) prices of newly constructed/under construction flats in my developed area or nearby new developing area is being quoted more than 1.5 times than 10-15 yrs. old flats in my developed area. some 1.5 -2 yrs. back, they were quoting almost same. i understand that there could not be perfect logic behind it , but only demand supply relation. however how can one determine fair values of a newly constructed flat and a 15 yr. old flat in the same area, say, stood side by side?