John,
The tariff was indeed collected by US customs so I had to pay the tariff etc to the person handling the import for me and he settled it all. I included the tariff in the invoice total to my customer and was refunded. This wasn't a problem as a customs broker was being used and the administration fees were know in advance so I could invoice my customer for the full cost of the import.
Shortly after the $800 limit was scrapped on postal imports, I had an order for some very unique accessories that I make and I sent them out, using one of the few courier systems that will even touch small value items to the USA. All was well until they invoiced me for the 'tariff' which was significantly more than the 10% figure my customer expected. On questioning this, we were assured that the figure was set by the local US import customs team, not the courier firm. I had no option but to pay up and ask my customer to refund me. This he did but under protest.
I made a decision at that time not to send any more items out to the USA unless of sufficient value to justify a customs broker.
I think that is the reason that the OP is finding that UK firms aren't interested in sending out any item under $1000's value. It is simply too much like hard work.
