ArtFire, for those who don't know, is one of the major competitors of Etsy. Like Etsy, they provide an online marketplace for handmade and/or vintage goods. Unlike Etsy, rather than have a per item surcharge for each listing, you can either have a limited account which allows you to post and sell a limited number items for sale for free or you can have an account that you pay for per month with an unlimited number of sales. ArtFire does not take a percentage of sales either - the flat-rate monthly fee is it. (Don't forget, though, that services like PayPal may charge fees for transactions).
ArtFire offers importing of Etsy listings so you can switch over entirely or maintain shops on both sites.
From the look of it, ArtFire may have some better, low-cost options for advertising and other marketing tools.
As I slowly consider opening shop I've looked at ArtFire and Etsy and have yet to decide which service to go with or whether to use both. Etsy has a huge following already, but ArtFire seems more flexible and depending on sales, etc., less expensive to manage.
In the interests of full disclosure, ArtFire is currently running a contest offering a table-top photo studio setup to anyone who blogs about the limited $5.95/month offer, so that is part of why I've written this post. But I also wanted to get the word out to my fellow crafters who already are selling online or who are contemplating doing so.