Title says it all really, 9 coke to make pretty much any Armourer 2 star item? That works out at 1125 tomes of philosophy for every single piece of gear you want to craft. Gear I should point out that's roughly equivalent to Darklight stuff IF you cram it full of materia.
Gods forbid you FAIL one of these crafts.
Why even bother leveling armoursmith at all? I'm not sure what the other DoH classes have to go through but I imagine it's much the same if that item list is anything to go by. I guess weavers/leathermorkers can make a whole bunch of crafting/gathering gear, but Armourers can only really make gear for gladiators, marauders and lancers (and their respective job classes) and they all get their AF gear at 45-50 anyways, so why do they need your services?