This should be seen in the context of a country where everything was in short supply, many people had no work and one had to try to exist by all means possible.
Street vendors used to sell cigarettes by the unit. One day I found one selling my favourite pipe tobacco. This had never been sold in the PX, and the nearest points of sale were Hong Kong or Singapore. How this street vendor came to have it on a regular basis I never found out.
Once we obtained three bottles of cider vinegar. My sister on a visit started to use it to wash or rinse her hair much to the consternation of KC.
A friend of one of KC's numerous cousins told of a somewhat frightening experience. In business, she needed to obtain a refrigerated truck. Such vehicles were of course unobtainable in Vietnam, and would have cost the earth to import. She therefore arranged to acquire one on the black market. She was put in contact with the competent organization which duly went about stealing one from the United States army. The refrigerated truck was delivered to her late one evening just before curfew. Inspecting her newly acquired vehicle she was horrified to discover on opening the doors that it was full of body bags containing the bodies of American soldiers killed in action. She had to get rid of it hurriedly. I never learnt if she was refunded for her purchase.
The Vietnamese authorities had confiscated a massive amount of 'military payment scrip', the money used by the Americans in all their internal transactions. One day the US authorities changed all the notes to catch the money changers and black marketeers with a lot of now useless money. The Vietnamese were angry the Americans wouldn't change the money they had confiscated for the new scrip or U.S. dollars.