Amazon has a very unique pricing setup.
I've seen stuff drop stupid low. For example, back in Dec of 2013 Jackson Safety was running a $100 rebate on their normally pricey WH70 hood (normally $350-400ish).
The $100 rebate off of the list price was a good deal. Amazon was listing the helmet for a while at $220ish (IIRC). That's when I brought the helmet, and for the $120ish I paid it was a very good deal.
Then Amazon put an instant coupon on the website that you could click and dropped the price down to $112 on Amazon, and when you sent the rebate in on that you would up getting the helmet for a few bucks.
Those people got an INSANELY good deal.
Sometimes the stuff shoots up high.
To check Amazon pricing history, you can get an extension called CamelCamelCamel. I don't know if it works with Amazon Canada, though. But if it does, it will show the pricing history on a graph for a given item if you click on the button on the browser toolbar. It is a very interesting tool to use.