Hi,
I have looked into the requirements of your project and started working on a proof of concept for retrieving the required information for a lot of Amazon/eBay sellers.
I have experience with Amazon and eBay APIs, there being a lot of other projects completed for different online stores on Amazon and eBay. Your task is possible using their REST APIs and I have also used other similar operations for adding products to cart/removing from cart, updating products information, etc.
Are there also other sources from which you would like to retrieve sellers information? If so, please let me know those sources so I can continue integrating them also.
Please let me know if you want to have a look over the proof of concept I have implemented and to discuss further the requirements/improvements of your project.
Really looking forward for a collaboration!
Best regards,
Razvan Faragau
RASisoft Software Solutions