I'm lvl 50 goldsmith, doing various other crafts in the range of lvl 20-30 at the moment. My black mage is lvl 35.
I usually have between 500 gil - 40.000 gil, depending on wether I just bought materials or just picked up income from my retainers. On days where the items I craft sell well, I'm able to add about 10.000 gil a day to my FC's savings.