Have a few empty makeup containers? Wash them out, dry them, fill with nail polish and let dry overnight! Your little girlie (Or boy) will absolutely love playing with them! My Mom did this for me when I was little and all my girlfriends who see the idea think it's genius!
This can be be really inexpensive if you use dollar store compacts and nail polish. I gave my daughter some makeup brushes from Forever 21 and a makeup bag to carry everything in. She loves it! We play makeup all the time.