How to Use T-money Card in Korea (Buy, Charge, Refund)
TL;DR: Buy a T-money card at any convenience store (GS25, CU, 7-Eleven) for 2,500–4,000 KRW, or at subway station machines.
Transportation
Incheon Airport to Seoul: All Transport Options Compared (AREX, Bus, Taxi)
TL;DR: The AREX all-stop train is the cheapest way into Seoul at 4,750 KRW from Terminal 1 or 5,350 KRW