little product comparison site

Hello
I am trying to create a website on WordPress that will compare the porducts of Ebay, amazon and aliexpress adn gives the best prices to the user
So please tell me what will be required to create such a site
like how can i compare the products of these three sites and their prices on single page usign some application( If you can mention the application software or site) also
what plugins and tools will be required to complete this projects
any other suggestions will be regarded
thanks