I urge people to cease trying to ban historical items from sale at fairs, EVEN if you find them reprehensible. They are hard, decisive proof that those eras and practices existed in more than books.
Gen. Dwight D. Eisenhower ordered that the Nazi death camps be thoroughly documented, photographed, and every kind of evidence possible obtained because he knew that eventually, someone would try to deny that anything had ever happened. Those shackles, locks and other equipment are the same kinds of hard proof of slavery's existence in the U.S. I've never seen items like that for sale, so they aren't to be compared to Confederate flags unless they were actually from the era of the Rebellion.
A small item like that can bring the reality of slavery home if used as a visual tool for children in a history class. In a teacher's hands, they can turn a boring book lesson into something very real as students imagine themselves in those shackles or being sold away from their families.
Some people are just into history or collecting. There is really no legitimate reason to limit their ability to purchase a sample of those items if they wish. You can't shut down things just because you find them insensitive somehow. There are far more positives to be had by allowing the items to be sold than by banning them.
Vermont's history is that of freedom, NOT slavery, and the ability to make decisions for themselves. These "cancellers" seem to have a lack of vision and are trying to enforce a very limited view of history.