I recently got an online submission from an artist who had part of her portfolio keds shoes. They were really cute so I investigated further and found out she designed them on a site called Zazzle
The site lets you set up an account and you can design a plethora of things from shirts to mugs to skateboards. I though the shoes were the coolest.
I don't think there is an upfront cost for the artist basically you load your designs, promote the items and then customers buy direct from the site. Zazzle has a base price set and you mark it up to the retail price and then after a sale comes through you get the difference. A pretty great deal considering you don't have to deal with any of the shipping, producing, basically all the non designing stuff!