We bought our tickets in the last 5 minutes before the train leaves so excuse my lack of photos of the Busan station. You just have to take my word for it that it’s very spacious, efficient and have a lot of dining options.
Our tickets to Seoul costs 50,600 won or about 2,160 pesos. The ride takes about 2 and a half hours. You can buy tickets on the machines like we did and just insert your cash and then it will print out these tickets.
The trains leave on schedule and there are plenty on the Busan-Seoul route and vice versa. There’s a train that leaves almost every hour. There were also food carts that pass along the aisle if you were ever hungry. :)