That is quite an interesting method. It's been so long since I have played so I don't remember exactly how I did it...I think I equipped Coral rings on everyone...
But I do know that fighting the Gimmie Cat (which is in the Dagurreo area, at the foot of the cliff,) repeatedly is a good way to make gil. You reap little experience, but hell, you get a lot of moolah if you fight them