What you could do is call studios in your area and ask
for Information on what they charge for certain
things and that would give you some type of idea as to
what things are going for in your area. Some areas
charge more some less. It depends on where you live
and how good you are and if you are in demand of not.
Trying to get started is not easy. Some times you have
to do things for les then you want, until you built your
reputation.
Also you don’t sell songs. You need a Book
“All you Need to Know About the Music Business”
if you are really serious about this.
EVe