Lots of easy money
On planet Nessa area 2 at the very end of this area search near the rocks on the far side for a chance to find a pearl mineral, which if sold is worth 10,000 gura. Also on planet Genchi, if you search behind the guy just before you see the monsters the is a chance to find a platinum mineral which can be sold for 3,500 gura. This can be repeated many times.