David Towne, head of the American Zoos and Aquariums' Giant Panda Conservation Foundation, said "it is not going to be manna from heaven for ten years.
"You should never go into it with the idea that you are going to make a killing. You can lose your shirt."
Four US zoos currently have a male and female couple, and Dr Towne 'policed' import negotiations with the Chinese.
He said real annual costs were likely to be almost 400,000 higher, with health care, staffing by imported technicians, and the cost of feeding the animals.
Edinburgh Zoo expects visitor numbers to increase by 30 per cent when the bears arrive.