You can easily do a Vegas-style party on the cheap if you get creative. One suggestion is to make sure that no one is spending real money on the games, unless your group of friends is used to playing for money. I would either use some kind of Monopoly money or I would get them to play for candy or prizes or something like that.
The problem with gambling themes is that some people really do have a problem with gambling and it's not always obvious who those people are. Using real money at what is supposed to be a light-hearted party could lead to a lot of hurt feelings, or even a fight and you definitely don't want that to happen.
If you've got games like poker going on, I'd make it clear that no one is to play for money. It's not like they can't do it in another setting, so hopefully no one will complain.