There are many shops along Takeshita Street in Harajuku that offers pre-assembled outfits to fit in with the cool kids on Omotesando. They can be relatively cheap. Most of the are in the Lolita/Gothic Lolita vein but there are a few punk style clothes too.
It’s somehow disappointing. I got into Harajuku fashion because of what those kids could concoct themselves, not because of what they could buy from a shop.