While going through the Nam-Yensa Sandsea, go to the northern most part of The Sandscale Bank. You will encounter an enemy named Bagolys. They are worth 448 to 676 experience points each and can drop Bent Staffs, which are worth approximately 1,300 Gil each. Fight them, leave, then come back. Repeat this as much as desired.

On the mission of the Blue Basilisk "Nidhogg", one of the parts of the roads is a place where lots of skeletons keep appearing. If they stop, go off two maps then return. The skeletons will respawn. This requires a lot of patience, but it will result in both experience points and Gil because you get Bone Fragments and Iron Helms which sell for 182 and 300 Gil respectively.