Origami is done by hands, so those who create it may produce wholesale only when they agree to a price/quantity of order. There is a site where origami makers post their creations and you can even customize the cards - Link hidden: Login to view
They can send to Vietnam and you can also view reviews on product quality within the site. Sorry but these products are not offered by suppliers listed at SaleHoo.
Hope this helps somehow. Let us know if there is anything else we can do to assist you.