Some authors are free with their autographs — indeed, some books by certain authors (see Louis Nizer) are hard to find unsigned.
Then there was Mark Twain. Twain sent a printed copy of this to anyone asking for his autograph:
“I hope I shall not offend you. I shall certainly say nothing with the intention to offend you. I must explain myself, however, and I will do it as kindly as I can. What you ask me to do I am asked to do as often as one-half dozen times a week. Three hundred letters a year! One’s impluse is to freely consent, but one’s time and necessary occupations will not permit it. There is no way but to decline in all cases, making no exceptions, and i wish to call your attention to a thing which had probably not occurred to you, and that is this: that no man takes pleasure in exercising his trade as a pastime. Writing is my trade, and I exercise it only when I am obliged to. You might make your request as a doctor, or a builder, or a sculptor, and there would be no impropriety in it, but if you asked either for a specimen of his trade, his handiwork, he woul be justified in rising to a point of order. It would never be fair to ask a doctor for one of his corpses to remember him by.”