Something seems off with the pricing in Withered Mhaire's shop. 1gp katana, 17 gp Mantis Mandible, lesser? Granted, wasn't much there for sale, but those prices?
So far as I know it's still the equivalent of a pawn shop where items are sold off at low prices rather than being trashed. It was intended to raise money for the poor, sad ill companions.
No bug. Items are sold as cheaply as possible there.