Instructions
Research online auction sites for Korean stationery. Ebay may have a limited-supply of Korean stationery. A better choice is the Korean auction site, Intrepark. You will need to translate the pages if you don't read Korean, but the search function operates the same.
Find a local Korean grocery store or Korean retail shop. A store that imports items from Korea may have Korean stationery. The manager or owner may also be able to import stationery for you.
Find an online store that sells Korean stationery. Stores such as Essentials, Artbox and Millimeter/Milligram offer a selection of Korean stationery.