The Camelizer can show you historical pricing on Amazon in the United States, Canada, Europe, and Australia.
Most of us use Amazon, but it's important to be careful because you can find better deals elsewhere. The Camelizer waits for you to open an Amazon web page, then click on the button to see the price changes. You can view prices from 1 month, 3 months, 1 year, or all time. You can also see third-party prices, but we don't see how that's useful without links to purchase them elsewhere. That said, you can be alerted that the product you want is available for less and use Google to try and find a better deal.
You can also set up email alerts if the price drops.
The Camelizer is useful for Amazon shoppers and easy to use. We happened to test the extension on Prime day, and we could easily verify the accuracy. The Camelizer isn't available for Safari yet, but it is expected.