I'd say a single issue since they can be graded and verified. Though in its self, any autographed book is only worth what someone is willing to pay for it. Generally though, like art, autographs of dead creators fetch more on anything. Books autographed by entire creative teams are worth more than one single auto. Adding Stan Lee's auto along a Marvel book's writer or artists automatically bumps up the value. When comes to having a signed trade, a first edition of the Dark Pheonix Saga will fetch far more than a later printing. So what do you have autographed?
It can be difficult to realize the value of an autograph without a certificate of authenticity. Unless you can prove the autograph is authentic, it may well decrease the value of what you're getting signed.
Yeah, really, having anything signed should be more of a sentimental investment rather than a financial investment.
This. I have stuff signed by Jim Lee and Chris Claremont that have Certificates of Authenticity (floppies and TPBs), but I dunno. If I were to sell them, not expecting much. I'd vote for single issue though. I'd assume the issue signed is a #1 or first appearance, etc. The concept of a TPBs (collection of issues) it will probably be reprinted again. Now, limited hardcovers, that's a different story.....
