I wanted to start a Design Agency offering unlimited Graphic Design Services. I have already seen others with the same service available now, but they only accept minor projects. I wanted to do real Graphic Design services. I wanted to seek advise on how I would price it. Then I also wanted to offer a startup package for startups.
Do in-depth competition research. Find people doing exactly what you do and call/email and ask for pricing. Make sure you have exact specs for the "job" mapped out and use the same exact details for everyone you call.
If you can't find anyone at all who does what you want to do you should dig deep and find out why nobody does it. There are probably good reasons.