I think the truth of the incident is in the detail of the story.
The Chinese claimed they were charged 1,200 baht for 2 Durian. Wichai the vendor said he gave them back 1,000 bht to get rid of them.
In another seperate incident it suggests the correct price of Durian is 75bht per Kg.
1,200 bht would be 2 very very large Durians.