i have a ton of signed books, some I got signed directly and others I bought when books were being released. I don't tend to buy second hand signed books as its a tad dodgy in a lot of respects but I will preorder copies to be signed on release. In this way they tend to cost the cover price and gain value rather than spending a small fortune.
'There is no future for e-books, because they are not books. E-books smell like burned fuel.'
Ray Bradbury (RIP)