Going to Vegas for my buddy's annual Christmas party. Started throwing around invites for dates. Asked 4, got 3 yes's and one 'lets do something else instead' - so i'm going to take the hottest one of the yes's.

I'm 24 and setup financially/professionally and she's a 18 yo college freshmen - likely broke like the rest of them.

How do I get investment from her (not necessarily financial) to take the "okay lol im so down" text and transform it into it actually happening. I was gonna make her buy her own plane ticket to get her committed but from where I am it's pretty steep fares, so was thinking maybe I cover half, that way she's still invested? Any other ideas on solidifying trips with chicks?