Making steady amounts of gil is easy...

- Treasure maps
- Dungeon runs
- Leve turn-in's
- Buying up market board items that are selling for less than the NPC sell price


Making millions of gil is harder, you need to pretty religiously follow the market boards and devote quite a bit of time to running around gathering materials.


Then again, unless you're looking to finance your FC's medium or large house all by yourself... there's no real need to try to make millions of gil. It's overkill really.