"Indestructible" is such BS. Literally, no one cares. The gold you save is negligible unless you are dying thousands of times a day, in which you should delete your toon. Whenever I get a TF or WF upgrade that turns out to be "Indestructible" I feel like the Devs just spat in my coffee. This is a very minor perk for Blacksmiths that should have been in the normal profession from the start. I am fundamentally underwhelmed.
I'll stick to the blacksmith garrison building buff until blizz decides its OP and should be removed.
WARNING: do NOT do mythic plus for the ingredients, will NOT drop. WILL drop in normal and heroic.