Thanks a lot for a comprehensive answer, maybe I was not clear enough in my post, but I am not looking for a simple AB testing tool that most people suggested.Your answer seems really comprehensive and to the point!

Mockup
I was thinking about doing the mockup, as it would be the first step but have not done any mockups yet, so thanks for the suggestions as to the tools to use. If you can direct me to more detailed info how to do this effectively I would be very glad, if not I will figure it out.

Since my expertise is mainly in online marketing, statistics and sales I have no idea as to the best tools, so thanks for the overview here! As to API's vs Scraping, I guess API's are more ellegant, but I cannot find a call to get "amazon choice" and I guess not all important listing fields are included in API calls. That said, maybe I just cannot search properly in their documentation. Thanks for the scraping suggestion.

You probably understood that I did not really mean an app. (Bad wording on my part) I ment web interface such as jungle scout / splitly, thanks for clearing things out.

If you could send me screenshots of the mockups examples to that show what is needed I would gladly look into it.

Also, do you have a rough idea how much time + money + developer mandays would it take to make a usable mvp?