It has been grown commercially for a while now in Taiwan. Not as expensive as it used to be. Supermarkets might not stock it, but you can get it easy enough online I presume. Loads of large farms started up 15 ish years ago. To be fair, it isn’t that profitable, and I think many farmers have realized this. But it’s easy, and still a good number of large plantations around. There’s a super large one, netted and everything, in Puli, Nantou. Must be available via coops or online shopping sites.
What he said (although it doesn’t match with what Explant said above) is that the fruit spoils quickly after picking. He usually just eats them or sometimes steeps in alcohol.