Welcome. I thing the thread (which started out in 2015) initially just attempted to pull together sources & leads for the local (meaning Calgary area) crowd. But a lot of time has since passed. Economy went through some fun times, some places no longer exist, pandemic made for a few more challenges, quite a few folks joined the forum from other regions who maybe have different resources. I guess I'm saying some of the info may well be dated & there has been no real effort to keep an active list per-se. Also people have different needs based on what they are building. It still might be worth skimming through just to get a feel.
If you have some information to contribute on this front, I'm sure it would be well received. From my own limited experience trying to source typical hobbyist quantities of lets say diverse but typical alloys, its a rather short & dismal list relative to my home town (Calgary). Lots of places in the USA like OnLine Metal, Speedy Metals, McMaster Carr who sell by inch or foot don't really exist to the same extent in Canada (aside from Metal Supermarkets). OLM will ship at slightly discounted UPS rates. Speedy is a UPS only shipper, so you really need a re-ship or border method to mitigate UPS dinger fees. McMaster is awesome, but technically only sells to CDN companies & institutions. Aircraft Spruce in Canada is pretty good for what they carry. Metal is heavy so we are at the mercy of shippers. Especially bigger quantities like full lengths of rod, pipe, bar, whatever usually shipping is the killer cross country. So 30% discount in one city or province gets gobbled up pretty quick to another region. Also, scrap yards seem to have changed over the years, region dependent. Maybe its liability or just extracting maximum value, half the places we used to frequent back in the day don't even want you on the property unless you are dropping off under supervision. Sometimes some Kijii deals or auctions have come up & the hobby metal ravens circled & scooped in, but not often.
Not sure if this provides overview but feel free to add any knowledge to the pile. There was also some talk of us just getting organized & maybe doing a group buy couple times per year so that a 12 footer of whatever could be divvied up. But it takes an organizer & effort. Mostly I think people are just driven by their own project needs & get what they need when they need it more or less.