I've resisted buying hex 5C collets for this same reason, they were spendy & I didn't have many applications. But I suspect the less expensive ones might suite my occasional purpose. What I wonder is how they fit normal hex stock? Usually the over/under tolerance on round collets is pretty close, max = nominal opening, min = maybe 0.030 under that? So how does it work with hex stock? The stock I've had in various materials varies all over the map. If it was much larger for example, would it fit the collet? Now you have no 'next size larger' to go to like a progressive round set.