Not for tourists only: I spotted a few locals drinking from coconuts, too, though I expect they didn't pay 30,000 dong (at the time, about a buck eighty-nine, like my weight). But figure in a photo fee for a wide-eyed visitor on his first day in Vietnam, and this fellow set a fair enough price.
Roaming coconut vendor
In front of the Fahasa bookstore, 60 Le Loi, Ho Chi Minh City
(From a November 2006 visit)