For your friend charge what you think is fair.
For your business in general, check to see what others in your area are charging for similar services. You don't want to give away your services but you also don't want to price yourself out of the game either.
A lot of it depends on what the market can bare. You say your from long island so I don't have to tell you how much of a price difference there can be from one side of the island to the other