I don't live in SK so take my information with a grain of salt especially since it's been some time since I read about it. Anyway I remember reading about someone from SK travelled to either China or the Philippines since there's hardly any restrictions there to get SN. I bought Chinese SN one time but the SN was rock solid inside the container.
Also South Korea is one of the hardest places to get concealed packages through from what I read. So I don't know how the customs works in your country especially if they're very strict. I vaguely remember someone else who somehow traded something for SN that's from NK but if I remember correctly they had to travel to the Chinese/NK border to get it. Other than traveling I haven't read much of people who got SN sent through mail especially in South Korea.