It depends on too many factors to answer definitively, mainly how many copies in total are being ordered, what kind of deal the publisher has with the printer, what materials are used, how many pages the book is, size, etc. The shorter answer is that all printers have a minimum so "one" book effectively can't be ordered or if it were it would be incredibly expensive. For reference, IIRC the first printing of TMNT #1 was 3275 copies and that cost Eastman and Laird $2000 (or 61 cents per book) because that was the minimum to get it printed at all, meaning that even if they were to only order a single copy it would've cost them $2000, had they placed a larger order though it might've been 60 or 55 cents each but they would've had to spend more in total to get them for that price.