Who will help me make an economical trip, starting from Chongqing and going to Seoul, Busan and Jeju Island in South Korea?

it's about 2 round trip to Shanghai by plane. There are more than 1 round trips to Qingdao. Chongqing 35 round trip. Taking a boat is not recommended. Although it is cheap. It will be exhausting. Arriving in Korea is at Incheon Airport. Go to Seoul by bus. There are subways and transportation. Dozens of dollars. You can take the bus. Almost 1. So take the subway. Convenient and affordable. Seoul can go to Busan by train or bus. Suggest a bus. Very comfortable. It's a long way. It is estimated that it will cost 1~2 RMB in 3 hours. There is only a plane to Jeju Island. By boat. But the transfer is afraid that you are not on the road. The price is unclear. It's estimated to be in the early 1 s