How To Make Saline Solution

There are a lot of places where you can find directions on how to make your own Saline Solution instead of buying it.  The instructions you can find seem very simple.  The claims that it will save you a lot of money while being able to maintain the quality and integrity of the store-bought version is one that seems to come into question if you ask a health professional about a recipe.  Basically, the instructions found are water, baking soda and salt which is heated together and then cooled.  The claims are then that this can be used just like the store-bought but there are no measurements of ingredients.  I think buying it is better.