There is just no such things. And right now I don't mean personal finances or watching your bank accounts. In this instance I'm talking about having different budgets for all the different resources you need to work on a book. For instance:
I don't care what the song says, time is not on your side. Between personal lives, other jobs, and that colossal time-sucking internet, there is never enough minutes in the day to write, edit, or market a book. Even if writing is your full time job and you have the discipline to sit at your computer for 8 hours a day typing away, there still isn't enough time. Because, of course, there is always a potential distraction. There are school visits to be made, and email to be answered. There are conferences to speak at, and blogs to be written on. And all of these things are important for your career as an author. You have to do them, but they take up time that you now don't have to spend, well, writing. So, make yourself a time budget (or as others call it, a schedule), and then whenever possible, stick to it.
Well, this one is fairly obvious, but budget your money. Unless you really and truly write for fun and never intend on trying to publish (and if that's the case, why on earth do you read this blog?), then you are professional, if unpublished, author and should treat your writing like you would any other business. And that means watching what you spend. There are all sorts of costs associated with being an author besides printer paper and envelopes for mailing submissions. There are monthly website hosting fees, potential travel costs, and promotional expenses. And have I mentioned postage? Sending manuscripts can get pricey, especially if you insist on tracking a package. Although your advance will repay and help subsidize these expenses, you don't want to go bankrupt. So budget your money, and spend it on what you think is the best investment. And always try to do as much for free as possible.
Now this one probably seems a little odd. After all, how do you budget a plot? What I mean here is to not put every clever idea you've ever had into one story. There are two reasons for this. First, you probably plan on writing another book someday, and you don't want to dry up the well on your first visit. Second, if you put every clever idea you've ever had in one book, you can conceivably overwhelm the reader, thus losing the impact the idea would have had if it had stood alone. For instance, think of all the clever things Rowling did when she created Harry Potter. She made one very cool world. But if she had introduced you not just to Diagon Alley, Hogwarts, and the general wizarding world, but had also thrown in Hogsmeade, St. Mungos, the Ministry of Magic, parseltongue, and oh, by the way Harry, the reason Voldemort can't touch you is because you contain a piece of his soul, well, that might have been a bit much for one book. And then she wouldn't have had anything to surprise you with in the next 6 books.
Those are some basic things to consider when budgeting. I'm sure there are many other things you can budget as well, but these are some of the biggies.