Are they rude or am I cheap?

It's after business hours, so I can accept the going-to-hell factor of posting from work to get this one off my chest... two of HLM's friends are doing a birthday party next Friday that's basically going to cost every guest $100, before gift, by the time it's all over. These people have money, so it's fine for them, but what stuns me is how incredibly casual they are about assuming other people also have that kind of money (and are willing to spend it on a week's notice just to see them). I would never throw a party that demanded so much of the guests--I would consider it unspeakably rude. Especially since this is a large party they're putting together, so we're going to get about 3 minutes' worth of conversation from these people we're paying $200 to be in the company of. *rolleyes*

I like these people, but there's no way I would go to this if it weren't for HLM. What do you guys think? Am I being cheap, and should I just accept that most people in our location/age bracket can do this kind of thing? Or are they in fact being rude? To me their attitude about things like this seems downright cruel. And I know from experience that I'm going to end up paying for a bottle or so of expensive wine I don't drink... the woman in question always splits the bill n ways no matter who has what, even in a small group, and this is a large group. Ugh. Why they treat people this way is beyond me. :(