The only one that has come close was guild.com and they were
bought by ashford.com last year and have for all intents and
purposes disappeared. They are still there but there has been
almost no marketing of the guild.com name since its acquisition.
But even on guild.com the people I talked to who had been on the
site for a year or more had very small sales volume if any.
While I have not had consistent success with my work on Guild.com, I
just re-upped my contract with them, precisely because they HAVE
continued their marketing efforts, James. I've certainly had some
problems with them as they've undergone various transitions (they are
no longer part of Ashford.com), but they continue to actively promote
their site and their artists, especially through catalog mailings to
their very extensive mailing list. Unfortunately for me, their
catalogs feature items that can be ordered (which only makes sense)
and I do all one-of-a-kind items which can't. Regardless, it
certainly beats mounting and maintaining one's own website given
limited time and resources!