Simply get a day off or go in evening.
Goto rimpa plaza, its literally like a toy store for cars
Park your car on 2nd floor charged parking no tension of any kind. Buy what ever you want to. If you don't wana take your car go and come back on a careem.
Experience what you buy. Online mei aksar ajeeb cheezein ajati hain and online is still expensive in Pakistan.
For audio if you are ok for used but branded stuff I can hook you up with a guy. He has branded used stuff.
If no alteration you can install new 6.5" speakers mostly grip to grip in 4 doors.