If you are considering selling your homemade bath products here is a good article to read:
This article covers FDA labeling rules, what sells and about selling. Under what sells click on the link on "Click on here to see that article" will lead you to information on saving money on bath salts and water vs. oil based fragrances.
You may also check out her archieves for other articles on other topics for making your own homemade products. I know I will referring back to her articles.