Well, kat, since you brought it back ...
When I first heard the song, as a kid, I thought "sold" meant the singer's indenture was sold. As when a man, or woman, was indentured for a number of years of labor, in return for passage somewhere, or upkeep, or whatever.
A lot of adventure books were tales of indentured servents who worked off their servitude and ultimately were freed. Some of them were bound to a "boss" of some sort, but he could "sell" them to another. It just seemed to my child's mind that the singer of AOC was not owned bodily, as a slave, but that his labor was owned until he repaid a debt.
Just another thought to further muddy the waters over the clam beds.