For a supposedly communist country North Korea is littered with souvenir shops - every Pyongyang site has a small booth selling books, postcards and other trinkets. Many tourists have expressed an interest in purchasing the metal badge with the Great Leader's picture printed on it that every North Korean wears; however, these are not for sale.
Insam (ginseng) is for sale in hotels, but prices seem ridiculously high. It claims to be from Paekdusan; insam from there has a high value for all Koreans. You may be able to pick up some more cheaply in Kaesong; ask your guide for advice. However, you can buy all grades of insam much more cheaply in the South.