Karachi is ridiculously expensive. The prices are stupid - eg . a 4 bed flat in clifton is worth about 2 crores these days. Lahore is much more reasonably priced.
Reason for Karachi being so high is that (a) no movement of manpower from Karachi and it is growing rapidly (b) no development outside of karachi for hundreds of KM. (c) people (businessmen) are absolutely loaded.