Plugin to allow users to sell items

I was recently commissioned to work on a website where users would be able to register and then post their work on the site for sale. I’ve been scouring the internet for a way to implement this feature, but I haven’t found anything that can really do what I need. The implementation would be very similar to Etsy.com or artistportfolio.net, where each user has a profile/gallery/and can set pricing for an item. Any pointers/help would be greatly appreciated!