You can also create facebook business or fanpage to promote your products.
CafePress maybe?
Ebay
Amazon
Etsy dot com
Try Zazzle.com. It's free. You only pay when your designs get sold.
My friends and I are starting a small business. We're selling Christian phone cases and t-shirts. We already have the designs, but we have absolutely no idea what website we can use to sell them! It doesn't have to be 100% free, but no crazy prices, either. Any help would be fantastic! God bless :)