The items themselves? Well there are japanese-specific stores that sell some of these items. But for the most part it's just taking clothing and coordinating it into specific styles.
For mori girl there is this website called "One-Piece Shop
And for dolly kei the shop called "Grimoire
" is most famous for its selection of vintage items that fit the style.
Your best bet is looking through fashion specific magazines because they'll usually have the stores listed on there.