In order to buy all gear sets available at level 18, a student must have a total of 15,180 Gold Pieces (GP). To maintain a balance, this total is slightly higher for Multi-Class students.
This means that students should normally receive a little less than Experience Points when you reward them for their behavior, when they complete quests, or when you use tools. Don’t forget that students also earn when their pets complete tasks and students’ parents can give them every day.
If you notice that your students gained so much GP that they’ve been able to acquire everything they can, don’t hesitate to use Random Events and Sentences creatively to remove some GP from their character. You could also create a shop where students can trade in their GP to purchase virtual or real items.