You have 5 options. From cheapest to fanciest:
1 - DIY with a bunch of layers of foam mat. IMHO, these suck (foam mat is only suitable to fake soft armor, no plates. The size you want. Cost 5-10.
2 - Fake hollow plates. Lots on chinese websites and probably on some canadian ones as well (airsoftdepot.ca and similar). Generally M plates and dimensions are usually off. 20-40 depending on where you get them.
3 - Good fake plates. Made of solid plastic and curved, like LOG Precision:
https://www.facebook.com/logprecision/?fref=ts. Weight is heavier than foam, but AFAIK lighter than real ones. Most sizes possible. Price varies.
4 - Actual training plates, non-ballistic, weighted. Team Wendy and others make them. Most sizes available. Price from 50/pair (used, if you're lucky) to $200/pair, depending which ones you get.
5 - Real used plates. Can be had fairly cheap in the US... but they can't be exported legally so I guess it's not an option?
Usually expensive in Canada.
I currently have #2, but #3 are my personal choice and they're on my shopping list.