Independent Nurseries and Garden Centers (the sellers) sign up and can instantly upload their items for sale directly to customers expanding their sales region of their niche products from just their neighbored to the entire USA. Since its niche customers who are looking for specific items customers find the site fairly easy through search.
The site is now doing about $2,000 total revenue per month. I'm taking a proportion of each sale. For now, I'm mostly covering cost, but hoping to work on some automated marketing tools to increase revenue.
As others have mentioned, my best performing referrers in terms of sales completed are often Forums (as opposed to AdWords, organic search etc).
The site does marketing via emails and some top products Google Ad Words, Facebook, and hopefully Titter soon. I'm using Google Analytics with the e-commerce plugin to build Adwords remarketing campaigns and plan to do Facebook rmarketing campaigns soon.
It's not totally passive as there's some support request, but I'm hoping to bring on an on-demand virtual assistant for support requests as discussed by the Internet Business Mastery guys: http://www.internetbusinessmastery.com/ibm-218-work-less-mak...