Quick con-type question!

I'm doing an event at work and there's a discussion underway about having what would be billed as a VIP/exclusive access dinner as a fundraiser. We'd have our main guest and hopefully a couple additional guest authors and then people could pay for a fancy dinner, getting to hang out with writers, and pre-view the exhibit before the opening. I know I've read about cons and things like that, and some cases there have been stipulations (you can talk to the guests but no autographs/photos), and I'm also trying to track down figures of what people would pay. We're throwing around the number of $500 right now. Can anyone point me towards things they've seen like that advertised online, or share experiences?