Place to go to buy an online business?

Hi there. I know you can go somewhere where people are selling their brick and mortar business. For example, there is a florist in my neighborhood with an ad on craiglist that he is selling. I’d like interesting in buying an online retail store and taking it over. Was wondering if there is a place online where people list this stuff. I know of craigslist but is there a popular place that focuses on this?