In general, when looking for the cheapest flight to Busan, try to choose a flight departing in October for the best deal.
From most locations, booking your flights to Busan around 55 days prior to your departure date finds the best deals.
Most of our users find that booking their departure to Busan on a Monday is the cheapest. Conversely, departing on a Friday seems to be the most expensive.
Generally, when visiting Busan, afternoon flights represent the best value. morning flights are likely to have higher prices.