I brought my slackline from the states. It is really easy to set one up with only 1" webbing and 3 carabiners. If you want me to show you how to set one up, I would be happy to do that. I can also take you to Jongro where a bunch of outdoor shops are located and make sure you get what you need. I have about 80' of webbing, but you don't need that much.
I live up in Ilsan near Daehwa on line 3. There is a place called lake park, near Jeongbalsan, where I usually go once a week to slackline. If you want to meet there, I can do that just about anytime.
PM me and I will send you my number.