Well, the town they are currently in that they're trying to get this armor made at is extremely low on supplies due to the famine they've been experiencing over the last 6 months to a year. So they don't really have much in the way of magical items, food, or anything really.
This craftsman took food as payment from the party. Food also spoils really quickly here (plot reasons).
Also, I probably COULD have found a ring, but they were low on supplies and they specifically asked for armor to be made.
I appreciate the direction though to the DMG and Barbarians Handbook.
From what I found since posting this, Armor that would make Natural Armor worse would increase it by 1. So the Armor could still provide some benefit, but not much.