Welcome to BYC. Glad you decided to join our flock. You can get in touch with members in your area via the Ottawa threads at https://www.backyardchickens.com/newsearch?search=ottawa,+canada. Hopefully someone there can help you locate some Buff Orpingtons for sale in your area. Please feel free to ask any questions you may have. We are here to help in any way we can. Cheers.
Once you have 20 posts you can use the buy-sell-trade forum (that includes a free re-homing section). It doesn't take long to get 20 or more posts, just jump in on conversations that interest you, or join in on the thread Michael O'Shay gave you a link to.
Good luck finding the birds you want and thanks for joining us!