My 43 cents (because 2 is just too low):
1) Ray and Sharon Courts ran the best shows of all time. They were incredibly great people and in it for the fans. The new guys want money.
2) Karen Cadle is the woman who set up the Jerry/Dick Van Dyke signings. She's trustworthy, as these bookings are part of how she makes her money. She's also Tippi Hendren's personal assistant, and she booked the convention appearances for her, Ernie Borgnine, Bill Daily, Barbara Eden, etc.
Here's her site:
http://www.karencadleinternational.com/
3) The reason you see so many people offering opportunities to get in on private signings like this one and the Dick Van Dyke are because Karen sets them up and lines the stores up as distributors. Think of it as a manufacturer selling their wares wholesale to stores, who stock them and sell them. Only, in this case, it's done by preorder. The stores take the orders and the money, take their cut, pass the orders along with the rest of the money, get the autographs, and ship them out. That's also why you see a difference in price between stores--they set their own. I don't know if Karen charges the stores per autograph or if its just a flat rate buy in, but the former sounds more plausible, as each store is roughly selling them for the same price, and if it was a flat rate buy in, the stores would likely try to undercut each other so as to take in more orders, which would help their profit, as opposed to setting them all fairly close, as if around whatever fee they have to pay per.
4) The NEW Hollywood Show also does their own private signings, which they set up and handle themselves. The Tim Curry was one of those, and the Ed O'Neill may have been too. With those, the show sets the rules and they decide every detail.