Hi
I am an integration expert, please have a look at my freelancer.com profile, most of the projects are API integration, one is Amazon. I have 100 percent completion rate with 5 out of 5 ratings from my clients.
As afar as this project is concerned, following is the approach.
1. Integration of your codeingniter system with Amazon:
a) Item creation API, available at amazon
b) Item Update API, available at amazon
2. Mechanism at your codeigniter system for trigerring API (New item or update in existing item), this can be automatic or with a mouse click, depending on your choice.
I can strong immediately, my promise is quality with customer satisfaction. Payment with milestone but after the satisfactory completion of the project.
Let me know when to start.
Thanks