Chinese WellTec are decent (currently done 71000 km problem-free). Nowadays kabli are too expensive. You can buy new in similar price.
Buy from Khan motors korangi road, Nippon autos sunset commercial, Umer autos pyala hotel (bufferzone), Faisal autos (haidry police station), Quality autos, Akbar autos, or Superway (all three are at water pump F.B area) whichever is near to you. These are considered good shops so just go to them and ask and they will tell you which brand is better.
Don't go to Sagheer centre Shohrab Goth or U.P mor New Karachi market. To these 2 places usually those people go who have little money and can't afford long-life, expensive stuff so the shopkeepers stock less-known and below average brands.
Have no idea about the price, because they keep changing (= increasing, metal just keeps getting expensive, plus the increasing price of yen/dollar). Rest assured, you will not be looted if you go to one of the above-mentioned 7 places.
Once you've changed the CV joints, always inspect for rubber boot damage. Once the rubber boot is damaged and the grease is expelled, only then do CV joints fail. Otherwise they have a very very long life. Make haste to replace the boot if you see one damaged.