You are approaching this problem from a wrong side. First you need to determine how much your service is worth to the customers, in monetary terms. Then you can base your price on that. Normally you would divide your service benefits into two parts: "commodity" and "unique". You would charge what it costs you to provide it for the commodity part and how much it is worth to the customer for the "unique" part.

Also note that educating the customer about the value (in monetary terms) that they will receive by using your service is the key to make this strategy work.