There was an interesting feature in the Sunday Times magazine this past weekend, about novelist Lionel Shriver, whose book, We Need to Talk About Kevin, won the Orange Prize. It was originally rejected by 30 publishers, and she and her agent split over it. But she kept on trying and eventually it was picked up by Serpant's Tail--and it has sold more than 200,000 copies.
"The royalties keep collecting like lint," the article quotes her as saying. She added, "I did have a rather satisfying encounter with the head of Weidenfeld recently. I ran into him at a coat check and he said, 'Mea culpa--I guess I made a big mistake.' The article says she believes publishers are way behind the curve on what readers want, routinely underestimating the desire for complexity, subtlety and moral ambiguity.
Another good model for hanging in there--which is what I hope you're doing, too.