I agree too, if you haven't paid for the party you have no business buying merchandise for something you haven't paid for. It's not fair to those who paid for the exclusive party. But by that logic, it should also not be ok to get Fastpasses for attractions for the period from 4-7 when you haven't actually paid for that time. But many see no issue with taking advantage of that loophole in the system. If that is allowed, and merchandise goes on sale in the park at 4, everyone who has paid to be in the park at that time should be allowed to purchase.