It's easy to find in Ho Chi Minh. Just start walking through Bui Vien in District 1, and you can buy it there from Vietnamese locals or expats. If you're a foreigner, you'll have guys constantly soliciting you as you're walking. Just stay out of the massage places on Bui Vien street while you're there.
Bui Vien weed is cheap, but it's Cambodian dirt weed. If you want the good stuff, search for Phạm Thảo on Facebook. She runs the Dreamer Hood dispensary pub, where you can get edibles, oils, and medical grade stuff. Keep in mind though that it's more expensive than what you're used to back home, probably because it's coming from farther away.
You can PM me...I've got a reliable hookup for med grade top shelf Cali sativa and indica. If you want the best stuff its around 500k per g delivered. I know you can definitely find it for 400k per g but its not as good in my experience at least. The stuff I get is just as good as anything I bought in SF. I refuse to smoke that crappy Cambodian shit they sell in Bui Vien.