London’s markets are full of little and big treasures. You go out ‘just to look around’ and you find yourself going back home with a poncho straight from Peru. Even if you think you do not need it, sometimes you just can’t help it! 
Camden Market has everything you need and everything you don’t … starting from a radioactive red cyber-punk outfit to hand made jewelry from around the world.
In search for vintage fashion and unique designer clothes I recommend Notting Hill with its Portobello Market.
If that’s not enough for you then go ahead and try treasure hunting at Brick Lane or Spitalfields Market. I doubt anybody has ever left any of those places disappointed.