With a little bit of thought, 1/2 an hour either on the net or with any of the books available in the library, you can fit yourself.
Having learned in this way, you can then go on to alter your position as you develop or change as a rider, learning more and adding to your knowledge about you and about your cycling.
By doing it yourself, you can experience the changes, you can aim for a certain position, you can alter your position and understand why the change does what it does.
Paying some one to fit you is essentially paying for one set of prejudices over another, and paying for what will only ever be a starting point is not something I would consider spending money on.
It seems to be very popular all of a sudden, and is the stock/lazy answer to any question about position on the bike, but it's not as good as learning how to do it yourself.