Well, the way it works is you have two options
The first is booking a 1hour appointment, you dont pay the makeup artist directly, but you have to buy at least 45$ worth of products after you get it done
The second option is a "demo" you can ask them to do your eyes, and they will do it for free, the only thing is that its an interrupted service so they will stop to serve other clients at the counter while doing your makeup. The service is to help you find products, but you arent required to buy.
Although, if you know you'll be needing soemthing, it would be nice to buy it after the demo because its good for the person who does your makeup, even though we dont work on commission. Only do this is if you have time though. And sometimes, like big holidays, we dont take demos at all (n i know new years eve we arent allowed)
I had it done for haloween once and although it was interrupted it tuned out beautifully
HTH