Back in the '80s, when these conventions were labors of love, there were no charges for autographs, pictures, or talking to guests. They actually appreciated and enjoyed speaking with fans. I have had famous comic artists draw sketches for me (I wish I knew where the Beta Ray Bill sketch by Walt Simonson is!) and spent an hour or more speaking with the guest of honor.
I can’t imagine spending substantial sums to stand in line just to have a few seconds with someone who has been on TV or in a movie.