Finding small and medium E-commerce store contacts.

Currently working on prospecting to get our first few clients on board. We’re selling to the e-commerce space so I am trying to find the most efficient way to get prospect information for small and medium businesses that sell the products online. The problem for me isn’t finding out the names and emails.. the problem for me is figuring out how to narrow down the companies strictly online e-commerce and small and medium business not large enterprises. Anyone have a solution to this issue?