Make your own chalk paint by using plain interior paint mixed with Plaster of Paris. 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.
There are A LOT of differences between milk paint and chalk paint. They are 2 totally different types of paint with totally different ingredients. They seem similar is because the finished product looks very similar. Here are some of the main differences: Adhesion Chalk paint is better in general