I know that its very difficult to create new sites now. Nowadays there are many sites in any area of business, so you have to make an effort to get to the first page in one of the search engines. But that seems pretty fair to me. I can share with you one marketplace where are ads
for sale by owner of e-commerces. Online business requires a lot of free time and at first you won't get nailed, you need a lot of money for really effective advertising and reputation building. I think that you could find a promising online store or any other site on this portal where it's possible to buy an online store from the owner, not a reseller, or sell it legally.