To come from Seoul to Jeju you will have to book a flight (180$) and hotel nights. Depending on the level of comfort you want here are the prices you should be paying:

Flight + 2 nights in 5 stars hotel (Hyatt): 180$ + 160$x2 = 500$
Flight + 2 nights in 5 stars hotel (Shilla): 180$ + 200$x2 = 580$
Flight + 2 nights in 3 stars hotel (Hana): 180$ + 80$x2 = 340$

You can book your hotel+flight package conveniently through our local travel agency partner Jung Tour.