Making cheap, natural body scrubs is the easiest thing ever.
Here are two examples, one for the bath and one for the shower:
For the bath:
I keep this mixture fairly dry as the idea is to stand in the bath and give your skin a good rub and allow the salts mixture to fall into the bath where you can soak in it.
For the shower:
I prefer an oilier mix for the shower so it clings to my skin a bit longer and it leaves my skin wonderfully soft.
Also, it is not worthwhile adding epsom salts which are more expensive than sea-salt as they will not be in contact with the skin long enough to be really beneficial, particularly as they are not dissolved when you rub the mixture on. For this job I mix a little coconut oil with sea salt - a mix of fine and course feels most comfortable when rubbing onto the skin. For a nice zingy shower to start the day I like to use citrus oils such as lemon and sweet orange. If the coconut oil is solid, melt it by standing a container in a bowl of hot water. I use about a teaspoon full of oil to a cup of salt. Again add the essential oils to suit your own nose.