Anything goes. People download "free" movies, TV shows, porn, and PDF/ePub copies of books.
People hoist things to YouTube and "monetize" them, even if it's somebody else's copyrighted material.
Let's have a bit of civility.
When Julie signs a picture, she's not entering into a business partnership. As in, "now you can scan this and sell copies."
She could sell "copies" on eBay and donate all the money to charity. So why are YOU copying and keeping all the money?
In a word DON'T.
Because it's RUDE. And you didn't tell her, "guess what, Julie, I'm gonna copy this photo because, er, uh, I want to make back the admission price for getting into Comic Con. And I'd like to make back the money I paid to meet you..."
Let's be a little more respectful and a lot less ridiculous.
PS, the items DO get removed from eBay as they are against eBay policy on counterfeit material and material being sold without licensing or permission.
That includes THIS:
Going back many years, people have routinely asked Julie to pose for a photo. Free. Even if it meant holding up the line. The reason? A souvenir. The reason shouldn't be to go into the dupe photo business. You didn't get a signed model release, after all. This was a friendly moment, not a business transaction.
So again, and this is coming not from Julie but from those who deal with the business end of things, please enjoy your moment. Enjoy the generosity of being able to take a photo at no charge. Enjoy your photo. If you need to sell it at some point, sell the original. Duping photos is just not nice or ethical. Thank you for your understanding.