At Busan Station, go to Daiso Busan Station (191 Jungang-daero, 10am–10pm) or

Busan Choryang (91 Choryangsang-ro). The 400ml gel ice pack with a handle is ₩1,000. Stock varies by Busan store, so check the map first. On flights, gel packs count as liquids and gels: over 100ml can't go in carry-on.