[COBI]

If you're not comfortable with asking them to pay some product costs and you don't want to charge them, another option is to use their makeup. It will give you some more exposure to adapting to different makeups and it will give you the option to say: I can use my makeup, but will need to charge you $xx or I can use your makeup for free, but I can't guarantee how long your makeup will stay "put" (unless of course they use the same brands as you.)

Good luck.