Well to know about the Bolivar black market and Continentals back door is pretty nerdish to begin with

I have experimented with AC's US/CAD conversion and found that AC has factored in an additional 2-3% on top of the exchange rate, which can be a savings if you can purchase tickets on their US website using a no forex CC.

In some cases the savings can be even larger I got 186 fare on their US website, when the Canadian wanted 226, but this is rare.

however the issue comes down to insurance (if you're using a CC that offers that). Canadian CC that don't have forex fees often don't have the travel insurance, and if you used a CC that didn't, you would have to pay forex, and I'm not sure the insurance companies would honour your claim since you are changing the country of residence, as that would amount to fraud.

PMUA's website on the other hand had significant savings on their Canadian website for codeshare flights on AC Metal, (some cases 50%) and I took advantage of that as often as I could. Margarita Girl had a post on that back in the day as well.

Expedia.ca is also pretty good at fiinding USD fares matched in CAD funds. Especially on other star partners (like US Airways) that don't have a Canadian website.