I've heard of several books that have gone this route, Noizy.
The additional component, though, is sales. I can't remember the book. I'd have to dig through hundreds of books to find it, provided I didn't let someone borrow it. Anyway, I specifically remember him saying that the one way he was able to get a traditional publisher was that he had sold so many of his self-published books. He would load of the trunk of his car and hit the road.
So in addition to having a high quality book, I think sales are also important to securing a deal.