I make my own version by using plain interior paint mixed with Plaster of Paris (affiliate link). You can find Plaster of Paris at Home Depot or Lowe's and it's really cheap. All you do is mix 5 tablespoons of Plaster of Paris with 2 cups of paint and 2 tablespoons of water. Just combine ingredients and stir well. It may even be a little lumpy, but that's okay. Once you brush it on, it evens out.