If you thought coming here would lead you to a car auction website, I'm sorry but it won't. I'm likely having the same troubles as you are.
A Google search reveals a frustrating series of interconnected links that never get you any closer to finding where a car auction actually takes place. It's the worst of the worst of search frustration. I did manage to find an auction somewhere, but it was restricted to dealers only.
If you're looking for a car auction, a better option is to scour the local newspapers, or even their online counterparts.
When dealers attend car auctions, reputable dealers will only bid on cars with no major accident histories and will have a mechanic check to make sure that the vehicles are sound. Often, these are lease returns.
Used car dealers are notorious for being shady characters. The worst of the worst prey on unsuspecting customers. They'll pay peanuts for a damaged car at an auction, (a car that a reputable used car dealer won't touch), and find a car report agency that shows the car as having an accident-free history. If you think you are getting a "great deal," then there's a chance the car was damaged.
BNN just ran a story about the company Car Fax, the car history reporting agency. Their histories are often incomplete. If you are on the verge of buying a car, either take it to a mechanic right away, or, if you don't know of a reliable mechanic near the dealer, make sure they have a two week return policy so you can get it checked out properly. Make sure you tell the dealer you are doing that, and that you expect to have your money back if the car doesn't pass inspection. Some dealers will try and force an exchange for another vehicle, but be vigilant and work a money-back-guarantee into the fine print.
When I went to look at a used Toyota Corolla at a dealership, they were asking $12,500 on the sticker price. I'd found a similar used vehicle for under ten, and wanted to try and bargain the dealers down. It didn't work, but the most demoralizing part was, as I walked out, somehow the final price had increased to over $14,000, with dealer fees and other hidden costs worked on. Some bargaining skills eh?
I walked away with no desire to return to that dealership.
Some dealers will bargain, others won't. Research beforehand whether you can wheel and deal, or whether the price is the price. My rule is to try and negotiate the final price to between 3% and 10% below the actual sticker price. Make it clear right away that you don't want to hear about "extra" costs. You don't care about them, you are sitting down and negotiating the final price and the dealer can put his list of extra costs away.
Walk away if you have to. If they know the deal is good for them, they'll bring you back.
If you are buying privately, the same 'mechanic' caveats apply. The two websites I use for used vehicles are kijiji.ca and autotrader.ca.
Kijiji has far superior search capability and is easier to navigate.
Autotrader includes dealer cars and may have a bigger inventory, while it's big downfall is that you can't do a search of your own city. Instead, you're looking at an entire region and, if you live in Kingston like me, you might have to drive for three hours to find your car.
Both are prone to hijacking, dealers in other cities putting cars up in the wrong category. I report them as spam on Kijiji, and get frustrated when reading them on autotrader.
Talk to friends and others about reputable dealers and their experiences. Google the dealers name and look for good and bad stories about them, although be wary, if a dealer sells enough cars, one is bound to be a lemon and get a bad review. But if they're trying to pass off damaged goods as having immaculate histories, that's another story and are the kind of dealership you definitely want to stay away from.
If you want to know about a brand's reliability history and general problems a vehicle is known to have, a good place to look is consumerreports.com. For a few dollars, you can get a one month membership.