My brother recently visited (to US from UK) and brought his guitar along with him. He didn't mention ANY problems, no threat of being retained, taxed, etc. I would have been scared to take an acoustic box in a soft gig-bag case on an airplane, but he did it and got away with it.

One instrument per passenger, or even a couple of different instruments, would seem reasonable for an amateur player. Two or three guitars for a solo traveler, on the other hand, pretty much reeks of professionalism, and a good-sized boxful of one's own CDs would be the kiss of death for someone hoping to pass through customs without questions, extra taxation, etc.

As far as I'm concerned, anyone hoping to "sing for their supper," busk, and/or play a few low-profile gigs as way to defray part of the expense of international travel should be treated as a private citizen and left alone. Only an artist or group on a tour designed to make substantial profit above the costs of traveling should be taxed and treated as a business.

I won't name names, since I am in no position to volunteer other people's services, but I have learned that there are some Mudcatters in the NYC metro area who serve as a sort of "welcoming committee" for fellow members visiting from across the Atlantic. Or, at least, that was happening a couple of years ago...

I would hope that ~ if you don't already have a US contact or two or three ~ some kind soul will contact you, volunteer to meet you at the airport, provide an address that you can provide your interrogators, and maybe accept shipment of your CDs before your trip.