Hi , replacing the digitizer could cost you around 2k rs from microsoft/nokia service center. If you get it done from a third party technician , you could be charged 300-400rs.
I strongly discourage anyone from repairing their device from third party technicians as they dont provide any warranty and are unreliable with the servicing
I supposed you are from India. Here in Bosnia i have had same problem one week ago and that cost me around 30$ or 20 euros. Idk how much this in your value but looks pretty the same if it is around 2k rs.