They're are a lot of shops in Islamabad for good rims, you just need to be a little careful about buying them. Repaired rims are not the problem, if they don't wobble and are balanced correctly, they cause no problems. Badly repaired ones destroy your suspension, you get a repair bill every time you take your car out of the garage. If you suspect anything fishy, just walk away with your money safe in your pocket. For tires, you can get them dirt cheap from "Sultan ka Khoo". They do have genuine tires but they are mostly smuggled ones so they are dirt cheap. Just check the manufacturing date and the country where they're are made, its written on the sidewall. If they're Japanese or even Korean, you're good to go. They usually don't have anything bigger than 17s so you'll have to order anything that is bigger than 17s. Always inspect the tires for any holes or punctures, even one means that they've been re-groved the "desi way"
I have a set of 18s if you're interested. They have brand new tires on them.