Replacing this part is a very complex and difficult job. It would most likely l, almost certainly require the replacement of your screen as it's almost impossible to remove without breaking (even by a seasoned phone repairer)
Cost. Screen $180, rear frame with bezel $20
To have it done professionally it would be US$250 (that's including a new screen, if your lucky you may find a repairer that can remove screens with out breaking, however very rare)