I grew up eating mangosteen in Indonesia and never knew it has gotten so popular in the US. But apparently, now that the import ban has been lifted, it's been all over the news, chowhound, etc.
It is supposed to be rich in antioxidants, etc, but to me most importantly it tastes good! I grew up eating it after all.
Now it is available in a few places in Los Angeles, that I know of. One of them is
645 W. DUARTE RD. ARCADIA. CA. 91007
But supposedly for a hefty price of $10.99 per pound.