What a budget trip to beautiful busan

There is a new airline to Taipei and only 100USD per single way to Busan, Korea.

That's is a very good deal for me to travel korea again. Because I still lots of korean won left from last time.

So my plan is TPE-PUS for 1 day in Busan then take a KTX to Seoul (2.5 hours). And spend 3 days in Seoul.(wanna see DMZ)
Gimpo domestic airport to Busan(1 hour) then to Taipei. No need to go ICH because too far and no directly express train. On the KTX can see the view from Busan to Seoul.