i bought a used amp for a litttle over $3k from a dealer in Cyprus. They were very experienced shipping to the US and filled out the shipping papers with correct codes to ensure no duties. However, because the amp was so heavy, it was pulled for investigation. I was contacted and asked what it was via email. They also asked me what the tariff codes were. I spent some time looking them and I too concluded no tariff was owed. I responded to the email and eventually my amp was released from customs, took a few days. A week later I got a bill from the shipping company for about $30. the US customs office charged them $30 for evaluating my amp and concluding no tariff was due. They were nice enough to pay it for me to get my amp released. I promptly paid them.
Jerry