Well, personally to me, unless they plan to provide you with a certificate to go along with it to validate your autographed item, then no, they should not be charging for it, as it would serve more or less just as a memento for personal reasons, not monetary gain. Money wise it wont do you yourself much good to have if you plan to sell to others unless you have actual proof of some type its theirs and not forged. If they are at least willing to let you take pics as they sign said object,then I guess so maybe, but really its a rotten deal either way. To me the right thing to do,the respectful thing would be to be willing to take time aside to to do it for free for the fans that otherwise attend. Attendance by die hard fans is pretty much what pays their bills. Fans don't show, then the actual convention isn't going to be willing to pay "celebs" to show up. They are paid to be present and attract fans. The other aspect of it would be that what little fame these guys have left is simply due to the die hard fans. The casual person isn't even going to care to have their sig. So in that respect, its def a rotten way to repay the people that keep you on the map so to speak.