I personally think that yes it's bad to expect that much. You're the one who decided to organize a party for a day that's all about you and your SO, it's not my problem how much you decided to spend on it. Even for my best friend's wedding I told him "You charge me something or expect me to give a gift worth X, I'm not going, it's your decision to do something special that day, you assume it, the day I invite you to a party I won't charge you or expect a gift."