Pricing is so difficult to determine, there are many factors to consider, you are going to need to do research prior to your proposals to clients. Find out what your clients are (and are,if you can) expecting to pay someone (barter), SOME HOW. Then charge in  accordance to fair market value of your service and product. There is no set price and most of us as competitors will not entertain giving you a dollor value estimate of your services to a persective client. Not being anything other then real in this response.