There is a fb group, Laos, Vietnam, Thailand backpackers or something of that order.
There are always, always new Honda Wins for sale on a daily basis. ++
I bumped into a young VN guy in Laos a few months back, he was mocking the young guys, traveling 2 up on their Wins' he says that they are worth about $100, but the price I see is about $250-$300, i think thats like a market value rather than the actual cost.
There are lots of posts about, engine rebuilds, upgraded suspension, parts list and claims of regular oil changes, and i think to myself, is it worth it? a bike that has probably had dozens of owners since 2000 who have all rebuilt the engine.
He says he is better off on his Honda Wave 125cc, which i don't doubt.
A met a guy in my city, he bought a Minsk from here,
http://cuongs-motorbike-adventure.com/ didnt seem a bad bike for the money. It also had decent Chinese canvas panniers. If you check the fb group you will see pick of big backpacks wrapped in plastic being strapped like panniers which is cool, but i have also seen a few people posting pleas after loosing their backpacks on the road. I think pack less and bring some enduristan or mosko panniers
I would love to own a Minsk here in Thailand, just to work on and look at, but I fear thats getting a distant dream.
IMHO i would suggest that if you want to buy a small bike for VN, Cambodia and Laos then try one of these, Wins' or Minsk's - it looks like you won't have any issues selling it during high season, there are as many 'wants' as 'for sales' .. Then come to Thailand, where you can buy a bike with a little bit of legwork or just rent one - that bike is no good to enter VN, which is why I say do it that way.
Im unsure that a VN reg'd bike is allowed in to Thailand after recent changes to the Thai system, and if you wanted to ride a Malaysian bike in from the south then the custom rules have changed recently, something about 30 days max, with no extension and restricted tot 60 days per calendar year .. i forget, theres so many complications at the moment. However, if you have a Thai reg'd bike its a little easier to travel Malaysia, and Malaysia although a great place doesnt seem to attract lots of long staying guests.
There isn't a one-stop 'best place' to buy a small bike in SE Asia, infact it's getting worse everyday.
++ ETS: Not new, obviously - old ones, but different to the day before,