eBay - The place to buy and sell easily.

 eBay Mobile

I think virtually ANYONE could sell something on this platform - how much money/profit you make is a separate issue/debatable, but the platform is still the most straightforward route to selling on-line if all your marketing and advertising 'facepalms' or you aren't into adwords.  Downside is the fees are high and the customers are often fussy.