I was part of an industry panel recently and at the Q&A bit someone asked how much they might get if they sold their novel. There was lots of umming and ahhing, and the concensus was 'it depends' and 'how long is a piece of string'.
This is true - you might get offered anything from a few hundred pounds to a few hundred thousand pounds. But I thought it might be worth putting down some sweeping generalisations about money.
When my first book was about to be sent out to publishers back in 2002, my agent told me that she wouldn't accept less than £10,000 for commercial fiction, and £2000 for literary. Those figures reflect roughly the minimum expected sales figures for a first novel from an unknown writer published by a Big Six publisher (that's the major companies like Random House and Hachette).
At that time, however, there was quite a bit of money around so hearing about deals for new writers at around £25,000 - 30,000 per book (literary or commercial) wasn't unusual. I'm not hearing that for new authors now - half that seems common. Very occasionally there'd be a mega deal for a first time writer, up into 6 figures. Rare then, rarer now (although it does happen).
Outside the Big Six publishers, expected minimum sales are lower, and the advances also lower. There are several established publishing companies that routinely offer advances of around £500 per book. It's not a way to get rich quick!
The level of the advance will determine the level of marketing spend the company means to give your book. A high 5 or 6 figure deal means a serious marketing spend, including advertising, special deals at supermarkets. My first book went out to reviewers in a red foil padded envelope and included all sorts of freebies the highlight of which was a specially printed pair of knickers (this is TRUE!) and there was also a deal with La Senza and WH Smiths.
This level of spend guarantees good sales. However, even good sales can be disappointing if a lot of money has been spent both on buying and marketing a book. I've met several authors who were dropped after getting great deals because their sales didn't live up to the money spent.
At the other end of the scale, traditionally low advances meant no marketing spend. However, this may well not be true for some of the new independent publishers who make up for the low money up front by having imaginative and enthusiastic marketing campaigns. If my choice was between a new publisher or an established (but not Big Six) publisher, I'd very much be looking at the marketing plan, rather then the money offered up front.
After all, an advance is an advance against royalties. If the book sells well, you 'earn out' your advance and receive more money. A small advance means you'll earn out quickly, and get more money.
Then there are other rights. These include foreign rights - you'll get some money from every country your agent sells your book to: small countries mean small cheques, bigger countries bigger cheques - large print rights, audio rights, serialisation rights. (It used to be that hardback rights and paperback rights were sold seperately, but now most publishing deals are for both together.)
So, in answer to how much money you might get, it depends, how long is a piece of string, a few hundred to a few hundred thousand. But, like winning the lottery, you're more likely to get a tenner than millions.