Um...500 ruppees is pretty standard among seamstresses in Karachi. Now if you go to a darzi, they might want more - not sure. Plenty of poor labor-family ladies in Karachi looking for stitching jobs, and they'll do it for 500 ruppees...which is what? under 10 bucks?
I couldn't believe it when some aunty told me recently she paid tailors in Karachi 500 for stitching clothes. Last time I was there 4 years ago, it was 250 and even that seemed so much for those living there. Dang.