I think I must have read this between 2003 and 2005 and it was most likely a recent used paperback. I've searched through my collection and Goodreads without luck.
I recall that the book had a pair of young humans on a non-human merchant ship. They may have docked at a merchant hub or network and one of them may have gone somewhere else. The main theme was of humans learning to become merchants and be able to be significant economically.
Thanks for any help.