I have 8 classes of crafting at lvl 35~38. Its very easy lvl up them at the same time. I have always HQ equip and I can craft materials from one class to another, so I don't waste money on markets. Also I have all cross skills.

After one month and a half, I have 1M of gils just selling armours, weapons and jewelry. (no materials, materias or craft/ghater equip).