So there are signed books, and everyone seems to like those. A signature takes 3 seconds and can triple the price of a book (or more, depending where you try to buy them). But for the real devotee there are doodled books! Like all collectables the added value is in the eye of the beholder, something ineffable. A first edition really isn't any different from a second edition (there are often far more first editions than second or third). A signature is just a tiny smear of ink) but it's a connection to the author above and beyond the mechanically reproduced words, and people like it. A signed first edition of some famous book from a few decades back can fetch tens of thousands. True, mine are unlikely to ever be worth more than a nice meal, but hey - they will last longer!
A doodle is something more. Not a signature that's bashed out thousands of times, but something chosen and executed with imagination, something that took time and thought. It may not be great art, but it's far more personal than a signature.
There's a site
Doodled Books that sells doodled books by all manner of authors. Some of them are very good, some very funny, and some even both. Anyway, it takes a helluva lot longer than a signature and they pay me £5 ($7.50) for doing one, but I enjoy scribbling and each one is a book sold and more than that it's a book someone is going to keep and look after.
So, if you want one here are the kind of things on offer. Go check 'em out!