Fair market value – Fair market value generally means the highest price, expressed in dollars, that a property would bring in an open and unrestricted market between a willing buyer and a willing seller who are both knowledgeable, informed, and prudent, and who are acting independently of each other.

see https://www.canada.ca/en/revenue-agency/services/charities-giving/charities/operating-a-registered-charity/issuing-receipts/determining-fair-market-value-gifts-kind-non-cash-gifts.html

A few people, especially those involved with charity scams focus on the “highest price” and ignore the words “knowledgeable, informed, and prudent, and who are acting independently of each other”.

You may also find the following case interesting:
https://www.canadiancharitylaw.ca/blog/russel_v._queen/