I was approached by someone that wants an incentive/rewards app built in the same style of one of my apps. In fact this person originally asked if they could buy a copy of my source code, but I said that I would rather create a custom solution to protect my own brand. The buyer is requesting a price for my services but this will be my first freelance job of this nature and I have no idea what to ask for. I will be designing the application (minus graphic design) as well as the server back end for user registration, login, credit tracking, and advertiser postback. What should I charge for development considering I will be able to use my current app and script as a template? Feedback from freelance app developers and others in the know is greatly appreciated.