I have found that guinea pigs are most definitely not as easy to care for as pet shops and photos make them out to be. The guinea pigs that are going to be brought into the classroom will not survive on your budget of $180. They will need bedding (that won’t stay clean forever, this will have to be spot cleaned everyday and changed over once a week). They need a water bottle, places to hide, a 24/7 supply of hay, food pellets, and a variety of fresh vegetables for each and every day. So, at least once a month, all new bedding, pellets, and hay needs to be purchased that will last you until your next purchase. And every week you will have to buy fruits and vegetables, spend every morning and after noon cutting them up and giving them to the pigs. AND the cleaning. guinea pigs (or atleast all 6 of mine) are very messy, every week I have to do a full clean out, which takes up at least 3 hours of my day. The pigs just aren’t fit for a classroom. You can’t expect the students to pay for nessecitys each month, for the next 5 - 8 years or rely on someone to properly feed and clean the cage. In no means am I trying to be mean. I think that another sort of class pet like a fish would be perfect.