Items that are "Too Expensive" and have been renamed stay "Too Expensive" even after grindstoning said item.

If you get an item enchanted to the point where it says it's too expensive, that item will never be fixable or enchantable ever again even after grindstoning the item. This applied for my boots and helmet, I'm not sure if it happens on other items, but I sent a picture of my helmet to explain what's going on.