Hi! I've added Amazon.com and Amazon.co.uk as example default engines just now in version 3.28.0, since I also find Amazon URLs to be hard to decipher. I suggest trying this URL:

httpa://www.amazon.com/s?url=search-alias%3Daps&field-keywords={searchTerms}

If you use other Amazon sites such as .co.uk, .de, .es, etc, you should be able to simply replace .com with that. :) I hope this helps and sorry that my reply comes so late!

And thanks a lot for the review. Really appreciated. ;)

Daniel