My kids make more than I did back when I was in college too. Then again look at the prices of tickets when we were young to what they are now.
Like I said, have no idea if $600-$700 is reasonable or not for her. I know my kids pull off their spending money at school, that is all their campus job covers. No way could they also put that kinda money away each month too, but they don't earn that much to start with. I don't think it is cruel or unfair if she is earning good money while going to school.