It's always good manners to call the bookstore and ask. Some are very accommodating, some less. Still, the smart move is to buy a copy from the host; bring others you want signed (up to whatever limit is set by the host, although Jim has a history of being gracious about people getting back in line after having the official maximum signed, as that lets everyone have that first shot at getting the max signed while allowing the patient a chance at more), but definitely be willing to buy one on-site.
