What's the best way to buy train tickets for travel between Seoul and Busan?

The KTX high‑speed train connects Seoul to Busan in about 2.5 hours and costs roughly 50,000–70,000 KRW if booked in advance. For regional trips, the ITX or regional trains are cheaper, around 15,000–30,000 KRW. Consider a Korail Pass if you plan multiple long‑distance rides.