In case someone in the future is in my situation regarding an upgrade to 20s and they live in the Toronto area or wherever. I picked up my vehicle in mid-August. For several weeks I looked on kijiji and FB Marketplace for OEM 20s and it was hard to find. I did post a wanted ad and someone contacted me during that timeframe and was willing to sell his in October after he changed to these, which you can get on mazdashop.ca for $1,359 CAD plus tax (MAZDA M012 ALLOY WHEEL (MATTE GUNMETAL) - 16"/17"/18"/20"):
That fell through as he decided to keep his OEMs for winter.
I later saw on my kijiji email notification someone post the OEMs for $600. That email came at 9:30 am and the page already had 63 views. I emailed they guy and he said already sold.
This week someone posted them for $800, which came from a 2021. He also switched to the wheels posted above. I was able to procure the OEMs from him. And good thing I didn't have to drive the hour to his house as he was doing a job half way between us so I met him at that site and did the transaction there.
I also posted on the Toronto Mazda FB group and on Marketplace an ad asking if someone wanted to swap their 20s for my 18s (both with tires) in case they prefer the softer ride on the 18s. I also adjusted my wanted ad on kijiji asking if anyone wanted to swap. One guy actually replied to that saying his wife wanted the 18s and he was willing to swap his 20s on the rims shown above, but then next day he backed out.
So there are options, but got to put a little work into and be patient. And some good info above about the TPMS scenario.
I will actually be keeping my 18s on for the winter as we won't be doing much driving and I don't live in a place with crazy amount of snow. And if snow is going to accumulate, we just won't go out. This will buy time until I decide if I want to do the 22s or not in the spring and decide what to do with these 20s.
Edit: And now on Oct. 13th someone has posted brand new 20s for $1,000 that are a 20 minute drive from me. Their ad says they bought a 2021 and immediately swapped out for some black aftermarkets.
And finally, a few days ago someone posted some nice 22s with the right bolt pattern and centre bore not too small with 40 profile tires, all in good condition (all seasons used only two years), about an hour from me for $1,500. But dammit, they're matte black and I'd have to paint, and the style is a little too different than what I'd like (pics below). They came off a Pilot. And someone 45 minutes away from me posted Vossens with a style I like (similar to the Aussie fella's car that Mike posted a pic of), with tires, for $1,200, but 35 profile tires.
Edit: Mid November someone 15 minutes from me posted the 20" OEM with almost brand new Bridgestone Blizzak winters on them for $2,000. I told him I still think that's pretty good value as both things are basically new and come with the TPMS. I said, if you need a quick sale and come down in price, let me know as I'd be interested. He said okay. I told him that I found 18" used winters with 10/32" tread as well that I was going to go look at for $250 in case I want to put them on my 18s but to still keep me in mind. I literally went out to run an errand and then buy those 18s and I come back and dude changed the price to $1,400 and it said SOLD. I was actually going to offer him $1,750 for everything and then sell my 18s for maybe $500 (post on this forum first) and then re-sell those 18s for more than the $250 I picked them up for.