I also do the same as you, and buy tickets ex-TPE as it is much cheaper than ex-HKG.. I work in TPE for around 10 days per month, and applied for a residence card... It was much easier afterwards to just show the residence card at check-in to avoid the hassle of explaining where my return ticket was... Also, its great using the e-gates in Taiwan as the lines can be quite long during weekends or holidays... I believe a spouse of someone who has a work visa or residency card can also apply for one as well... would highly recommend getting one yourself..