Ross,
Trades don't count??  Then what does the "value" we write in on that
customs tag mean anyway?  If it is related in any real way to the
items in the box, then what difference does it make whether I  pay
you for those items in cash or merchandise?  If a diamond is worth
$1,000 when I pay for it in cash, is it worth less if I pay for it in
rubies?  or pearls?  or a motorcycle?  or seashells?  For income tax
purposes, the government considers barter (that is, trading) to be a
sale and a purchase by both parties.  I can't escape paying sales tax
on a mobile home if I acquire it by trading a truck for it.   The
powers that be see it exactly the same as a cash transaction.  Why
wouldn't customs see it the same way?  Note, I am not touting any
particular position here on the question of whether or not we should
declare the cash value of shells we ship.  But, whichever side of
that fence a person is on, I can't see that the declared cash value
is dependent on the form of currency used for payment.
Regards,
Paul M.