Which is d cheapest form of transaction method in Vietnam. Traveller cha, forex card, debit , credit cards
Cash - no admin / transaction fees when you change money.
In order of preference: cash > credit card (with no foreign transaction fee) > debit card > forex card > traveller check. Well, I have never used traveller checks, since it seems like a hassle.
Cash... Only cash.
Cash! I think you should exchange money to Vietnam dong (VND). Because, if you use credit card, you must plus 3.3% for bank fee (transaction fee)