It took me about 4 years of hands-on lab practice and reading to become competent with formulation although I was able to produce my first products by knocking-off existing formulae. However I now find myself replacing the early ones because I can see better methods / ingredients.
Apart from the time, I have about 150 raw material ingredients, a small personal lab, and a few thousand $ worth of equipment. If you are looking at opening a retail store then budget around $30,000. If you’re not looking at opening a retail store then you will need to spend a lot of time considering distribution methods. Online may work for you IF you live in an advanced country where people are used to buying on line.