Dear buyer,
I must say that your requirement is really going to be a complex one, as you stated but we have pretty good understanding and experience working on these features (eBay, Amazon, Magento etc) and I assure you that our experts will delivery an exact version of need.
We will prefer to do this in core PHP language to be compatible with all the APIs provided by these domains. This seems very much doable to us though "competition" module may be the one we need to drill down more; how to achieve that.
As soon we commence the project, our Business Analyst will prepare complete FSD (functionality specification document) and for sure would required to have couple of rounds of discussion with you. Afterwards, you will get a complete project plan which will outline deliverables with specific date. Finally, our DEDICATED team of developers, designer and a QA would assure to achieve your desired application.
We believe in long term relationship which bound us to work till 100% satisfaction of our clients. It will be our great pleasure to be associated with you.
Please feel free to share your observation.
Thanks,
Prakash Sharma
Hitaishin Technologies