New sealed sets in bulk?

Hello again! I have a math project, and I want to teach my class how to build bionicle. I need help trying to get sets for 28 people including myself, so please help me! It is a group project, so if everyone contributes in my group (3 people total), I have to buy 9-10 sets. Please leave suggestions on what sets I can buy in total for under 20-30 dollars. Thanks!