considering the boss coming up, I would suggest that if you levelled up to a comfortable level, you'd probably find that you have sufficient gil. Barring that, if they let you in at Bal Castle, grind on the Objet d'Arts in the basement (throw softs or use lvl 5 doom). I think they drop about 500gil/enemy. Or go to the Seal Castle Kuza and fight shield dragons for 1000gil/enemy (use !Control)