Here are some recommendations for online stores in Korea.
KPOP Merchandise

BIGHIT(BTS)

BIZENT

FNCSTORE

MD GOODS

SM TOWN & STORE

SOUND-WAVE

STAR SHOP GOODS

SYNNARA

WITHDRAMA

YES24

YGESHOP

Beauty/Cosmetics

AMOREPACIFIC

COSRX

INNISFREE

KRAVE BEAUTY

NATURE COLLECTION

MEMEBOX

OLIVE YOUNG

ETUDEHOUSE

THE FACESHOP

VT COSMETICS

 

Jewelry

DEEPBROW

FRICA

HERMOSASTYLE

J ESTINA

NUMBERING

MOLANG SHOP

OST

WANDERING YOUTH

 

 

 

Women's Clothing

BABINPUMKIN

BEGINNING

CHUU

ICECREAM12

LALABONG

LOVE ME

MEJIWOO

MUSINSA

MILKCOCOA

SONYUNARA

WCONCEPT

Men's Clothing

ABOKI

ANOTHER YOUTH

ESCSTUDIO

HI FI FNK

HIPHOPER

MEOSIDDA

MUSINSA

ODDGALLERY

RAUCOHOUSE

TOMONARI

 

Sports Wear

DESCENTE KOREA

ADIDAS KOREA

FILA KOREA

MLB KOREA

NEW BALANCE

NIKE KOREA

PUMA KOREA

SPRIS

 

 

 

Lifestyle/Misc

10×10

MONOPOLY

 

Shopping Portals

11ST

AUCTION

CJMALL

COUPANG

GMARKET

GSSHOP

INTERPARK

TICKETMONSTER

WEMAKEPRICE

Second Hand Market

BUNJANG

JUNGGONARA

HELLO MARKET