Hi, I'm a beauty therapist, not a hairdresser.
A hair treatment cost is based on how much work is involved. Some techniques require more experience so the hourly charge will be higher. And some heads of hair are more work than others, depending on your natural hair colour, whether you still have bleach or dye on your hair, what condition it's in and how long or thick it is.
It's a bit like asking how much it will cost you to rent a place of your own. The best answer is "what sort of place are you looking for?" Your hairdresser will need to see your hair and your photo before she can tell you what technique will be required and how much s/he needs to charge.