Best thing I can recommend is once you reach the place with the 10,000 Gil Justice Monsters V machine, play it and reach 99 chests. Then sell the reward for 500,000 Gil. That will cover all your expenses for a while.
You can repeat this for more gil or you can use the reward (Wind-Up Lord Vexxos) as a powerful elemancy catalyst. Turns the 3 elements into their highest spell forms, Flare, Freeze etc and gives you 56 or so copies of them to use. Crazy stuff.
Where is this magical machine?!?
And also, when I played that game it was impossible to lose, so I just quit and got nothing. Is it safe to quit once you hit 99 chests? Or is it possible / feasible to lose on that machine?