It seems that this is my biggest trouble in being a smith. I always end up having to buy steel ingots or corundum ore. (the former is always more in stock than the latter)
Well this happens with quicksilver/moonstone/malachite as well... but corundum should be fairly more common given it's value compared to some other ores.
Only good source i know of is in through fort dawnguard.
-I LOVE SCALED ARMOR. I'm wearing a full set, though unfortunately i can't make the horned variant OR upgrade it . (come-on beth just add a goat hide/horn into the smithing formula)
-I also find that nordic weapons and the heavy nordic shield look amazing with it.