I know I'm a minority on this one, but I don't agree with the common opinion that it is 100% on the host. Even if it's the host's mistake. The person puts the effort in to create a great night for his friends, and then his "friends" let him/her eat the costs?
For me it's no different than if someone organizes something, a trip for example, and let's everyone know "it's gonna cost X dollars per person". Then if that person says "crap, due to [some reason, maybe an error made by the petson, maybe bad luck, etc] the cost when up", are you really gonna let the person who did all the work eat that whole cost??
The title asks about etiquette. In my book, the proper etiquette is for the host's friends to act like friends.