Any student who pays the exam fee may write an AP exam, and may take as many AP exams as they want. you do not have to have taken an AP course in that subject in order to challenge the exam.
In the YCDSB, students pay $130 (Canadian) for each exam administered. This covers the exam fees charged by the College Board (in US dollars) and the cost of administration and shipping of the exams. St. Brother André CHS may be able to subsidize a part of the exam cost for students demonstrating financial need.