Your question is specific enough to get an answer directly from the school, so you should call that particular school & ask how much the position pays. Generally speaking, school bus drivers don't make a lot, not too much over minimum wage.
The salary for a school bus driver at First Student has not been disclosed. You can contact the administration during week days and confirm on the issue. You can learn more about school bus driver career at First Student at http://www.firststudentcanada.com/First-Canada-jobs.