Hi David,
While working in India on my book Elephant! a young chap was incredibly helpful to me in numerous ways. When the book was published I offered to send him a free copy and he told me that he would have prefered to pay for it, on the basis that if he paid, it would have a greater perceived value for him. He didn't have two beans to rub together, but he did give me faith in a small minority of the human race.
I too get asked by people for free copies from time to time. Divide the cover price by the number of pages and then you realise what a great bargain each page of a book is.