Mega bestsellers usually get all the press, so it's easy for a writer with...modest...sales to feel inadequate. Take my word for it. Fixated by Facts: Nonfiction taking over includes sales figures for a couple of well-known literary writers and quotes Ron Charles, fiction editor for the Washington Post's Book World, as saying, "In fiction, less than 10,000 copies is considered successful for a first novel."
I wish this kind of information was commonly known. Not only would I feel better, personally, but I think many people going into writing have unreasonable expectations about sales and income. I also think many readers think a book that doesn't sell like The DaVinci Code or any Harry Potter must be a dud.
Be sure to check out the last paragraph of this article, too.
The link came from ArtsJournal.com.