I don't know if others thought about this before me ... It took me one year to realize this... (note I own the Pal version) bust just as soon as you can create new allies at the Guild (after defeating Virgo for the first time) you can become extra rich, I created new characters put them in my party and after having sold all of their equipment I obliterated them and create new ones, I got already 100.000 by the time I got in the 2nd floor...