I was over there briefly last month and tried craft brews from a couple different breweries, Pasteur Street Brewing and FURBREW. Both were excellent.
Sounds like there are a few homebrew stores in HCMC and Hanoi, but I'll be in Danang so I'd have to get stuff shipped. I'll also be there for just 2 years, so investing in gear doesn't seem like it'll be a smart move. I'll probably just take a break and start up again when I get back.