A decent Margalla even today is atleast 250K probably more in 250 you can get a good condition older model margalla.
A Khyber on the other hand will be in pretty good condition in 250K but still the model you will get will be old and in Karachi Particularly these cars have been really abused. i personally have one and it is a real good car.
A mehran on the other hand in 250K will be much younger in terms model.
all of them are easy to maintain, CNG friendly and all mechanical parts a available.