I did wonder whether that might have been the reason that USPS turned the ebay set around on me.
It was just a used amazon set, but without knowing how much it weighed it's hard to estimate freight cost. They were sending it with the ebay international shipping program, so I had faith it would be okay... Clearly not!
I'll keep you in mind though, it's entirely possible that paying the freight from NZ works out the least painful option