Import duty is 3.2% I believe, unless the instrument is old (>100 years, maybe) in which case there is no duty. See:
http://hotdocs.usitc.gov/docs/tata/h...er/0901c92.pdf
Not sure how they value the instrument if it's not new, an appraisal that you provide I would expect. I suspect if you have owned it for some time that there is no duty.
I am not familiar with freight forwarding, and whether it is done by air or sea. If you send it by boat it will take about 2-3 weeks to the east coast or 6 weeks to the west coast of the US. Do you want your bass in the hold of a boat for this length of time? You might also need more robust packing/crating.
The rate quoted above for FedEx air freight is what I'd have expected, or less. Trying to take it with you on a plane is a well documented challenge. There are size restrictions for baggage. Some have talked about buying an extra ticket, but I doubt you could fit the bass into a coach seat if that's how they do it. You should check the forums here to get better info, and also check the ISB site:
http://www.isbworldoffice.com/resour...your_bass.html
Good luck, and let us know what you do and how it works out,
Jim