Are there any months where car or house prices usually drop in Canada? Is the difference noticeable enough to justify the waiting?
In Canada, be careful about buying a house in winter - especially in regions that get a lot of snow. Even after getting an inspection, there will be a lot of things you really won't know about until spring. You can clear some of the snow off the roof to check its condition and miss a meter square section on another part of roof that is in imminent need of repair. You'll miss the fact that they had previously kept a small army of dogs in the backyard, and you don't actually have any grass...
Houses do go down in price in the late fall/early winter usually bottoming out by January. But unless it's your first home and you're willing to put up with a few surprises, I wouldn't consider it worth it. You'll have to contend with a much smaller selection. Also, for any home other than your first, you also have to be able to sell your existing home.
Car prices drop significantly in late fall, when winter is coming. That's cause of people don't want to bother with cars in cold weather, so they don't buy vehicles. That is in Russia, which is located exactly in the same climate zone as Canada.
House prices varying on much more parameters, but location is always important, so prices behaviour best known only by local rieltors.
NEW car prices do tend to drop in price during the fall. Though a lot of that is due to manufacturers trying to clear out the current year's models to make space for next year's models.
There are websites that allow you to purchase a report detailing the dealer price (what they pay) for the car you are looking at. Car cost Canada is one that I have used and you can get a discount on the membership if you are a CAA member. Once you know the dealer price, you will have a better idea of what you can negotiate the price down too. Sales people are more willing to give you extras, like mats, service packages, tinted windows, etc, instead of price breaks.
If you are purchasing a used car, there is a black book of automobile pricing that gives you the price of the vehicle with a low to high price range depending on the condition of the vehicle. I'm certain that all used car dealers base their pricing on that book. So there isn't too much fluctuation in price between dealerships on used vehicles.
Not too sure about housing. I tend to agree with Chaotic that pricing will vary greatly within a region. Ex. close to a good school, libraries, parks, etc. There typically is a slow down in sales during the colder months and you may be able to get a better price because there are less competing offers for the same house/property.