Now that you’ve got all the pieces, here’s how the mechanics of a typical deal would unfold:
Suppose you’ve a product that only has a user base of 25,000: very respectable, but probably not enough to get a publisher to do a book about it on its own merits. You figure that you can use 10,000 copies of a book for a marketing effort as a giveaway item bundled with another product, and another 10,000 as a registration premium for this product, for an initial order of 20,000 copies. The publisher figures that they can probably sell another 3000-5000 through their normal channels, so the total copies in the market will be about 25,000.
Assuming a cover price of $29.95 and a 75% discount, each book will cost $7.49, so 20,000 copies will cost you $149,800. You’ll probably need to pay the publisher $60,000 on signing the contract (before the author starts writing), another $60,000 on publication (the day the book first sees the light of day), and the balance within 90 days. Depending on how you’ve set up the contract, you’ll probably receive a large portion of the books you’ve purchased at publication, and the remainder within a few months.
By the way, if your marketing effort is very successful, you may use up your pre-purchased copies of the book sooner than you expect. If you do, there’s no reason why you can’t go back to the publisher and ask them for another 5,000 or 10,000 at the same price. They’ll be glad to do this: after the first purchase, every additional copy the publisher sells is gravy. You should be able to get the same or similar terms. (If you’re really planning ahead, you’ll want to put a clause in the original contract that guarantees you the option to buy additional blocks of, say, 500 or 1000 copies at the same price.)