[427 S/O]

Plums, as a customs broker I can tell you the average U.S. air import charge is about $65, not including merchandise processing fee, duties (if any) and shipping from U.S. port of arrival in the U.S., to your residence. BAX may have other charges and, they may have classified your items incorrectly?.
I left the import field to work in customs compliance but keep in touch with a number of brokers across the U.S., send me a detailed list of your items and I will let you know customs duties and fees. If you plan to import in the future, let me know and I will put you in touch with a couple of brokerage firms that don't have exorbitant import service charges, customs charges will always apply.