yeah sunglasses is a particularly touchy subject for me.
Short answer; get 1000-2000 in your pocket. Go to any eyewear shop in tariq road/bahadurabad (the smaller the shop the better). Have a look around if they're sporting "We are the official carrier of XYZ Brands in Karachi" tell em to shut the f*ck up and just give it!! Remember; NO MATTER how much the shopwala convinces you its A copy or B copy or XXX copy that will give babes f*cking orgasms when you wear it tell him to shove it. Dress in
meli shalwar qameez if it makes you feel better!!
~2k is max. If you still cant find anything pm me I will tell you some good shops.
I can also recommend you shops where you can buy ORIGINAL Rayban/Oakleys etc but each frame is ~15k starting. And woe unto you if you wear prescription sunglasses it will double your cost.
Bottom line; Go for (sasti) copies or go for originals. Imo sasti copies can be bought from those road-wala bois.
Also regarding "Original" sunglasses read the following:
Read these:
---------------------------------------------------------
Eyewear Brands | Luxottica
Luxottica Group S.p.A.: Information from Answers.com
Eyewear Brands | Luxottica
Are Designer Sunglasses Worth the Price? - WSJ.com
----------------------------------------------------------