Another good method for endless money farming is to break large boulders using Tauros. Go to Poni Coast, above Poni Plains, and there are four large boulders you can break in a row. After breaking all of them, leave then return and the boulders are magically restored. Rinse and repeat. They sometimes drop:
- Stardust $1,500
- Star Piece $6,000
- Comet Shard $30,000
This is a method I saw on a video from Verlisify. I make on average anywhere from $50,000-$100,000 in five minutes.
Hope this helps. It is the most effective method I have seen so far.