Thanks for all the comments folks.
The seller got back to me again because he found a clause on the customs website that says certain photographic items may be subject to customs inspections. The clause in question refers to potentially dangerous chemicals and content of films (e.g.: porn movies which
are banned items)...
He also can't get it through his head that in any case a binocular case is not actually a "photographic item"- not in this universe anyway. (The good old Aussie phrase "thick as two short planks" comes to mind.)
I have told him that he won't be getting my custom- although he doesn't seem to want it anyway! Certainly a funny way to do business.