I second the recommendation to build up gil chaining skeletons in the Lhusu Mines. That's how I built up money enough to pick up the items I wanted before moving on around that time. In general the bones yield more gil than the sandpeople. Some levels will come along with the gil-collecting, so I wouldn't worry about that.

As for the spells, I can never remember where everything is, but I would check Rabanastre, Nalbina, and Bhujerba each, then just check incidental villages and stuff for anything else, but I wouldn't make it a point to search them out unless there's something specific you're looking for.