Autographs used to be a way of proving you had really met a famous person—kind of like a signature in a hotel guest book would prove that Abraham Lincoln had actually slept there. But today, most autographs that are collected either disappear into a drawer so they can one day be discarded as trash, or end up in collectible stores or online auctions like eBay.

“I remember whenever I got good grades in school, my mom would say, ‘Congratulations, do you want to go to What’s on Second?’ (a local sports collectibles store) says New England Patriots Superbowl-winning quarterback Tom Brady. “I’d always say ‘Let’s go!’ The card market is pretty amazing. When you have something signed by someone you admired as a kid, you feel like you have a little piece of them. It’s just continued to grow, mainly because people seem to have a fixation; they like to buy baseball cards. We’re asked to participate in a lot of card shows, and it isn’t until you get there that you realize how big a deal the card industry really is. Shoot, the whole memorabilia industry is amazing now. To think that Luis Gonzalez’s gum went for as much as it did, that’s amazing to me.”

Luis Gonzalez’s gum really did go for a large amount of money on eBay—over $3,000.00—leading Seattle Mariner’s reliever Jeff Nelson to try and sell bone chips from his elbow on the service soon after. Unfortunately for him, eBay has a rule against selling body parts, so Nelson’s auction was soon cancelled.

But an autograph can just as easily be junk as it can be treasure. Brady knows this from experience, having had to tell more than one memorabilia store owner that a football in their possession that was supposedly signed by him was really a forgery. “When you talk about how big of a business autographs are, and how much money is involved, you can understand why people are trying to cut corners. I know I’m a little apprehensive when I see older guys standing outside waiting for my autograph.”

The only way to be sure that your piece of memorabilia is genuine, whether it comes from an actor, athlete, musician, or serial killer (yes, people collect autographs from them too) is to make contact with the person yourself (well, maybe not the serial killer). This can be difficult with some celebrities, but others are very easy to track down and are more than willing to offer you their signature for their collection. If you’re smart, sane, and prepared to do a little home (and leg) work, you can contact just about any celebrity out there and let them know how much you appreciate their work.