Looking for eCommerce data

I'm building a site that is a search engine for eCommerce newsletters (https://inboxes.com) so users can browse latest offers and see real time stream of incoming newsletters. Currently following about 300 retailers mainly in US but some global ones as well.

Looking to get a big list of links of the biggest / best US online shops to add to my site.

Anyone has such a list or can direct me to a downloadable one ?