Probably the best PHP class library available complete with explanations and demo. It is based on a previous library at the following address: https://github.com/Exeu/Amazon-ECS-PHP-Library which is also very useful.
Another PHP class not updated. It could be useful for code analysis.http://wern-ancheta.com/blog/2013/02/10/getting-started-with-amazon-product-advertising-api/
Two good articles useful for an easy and quick understanding
Amazon documentation is the starting point for further development.
Important advice on correct use of AWS access key.