If you look at it as getting your bow "tuned" yes it is expensive. It cost around $100. When you consider that you are getting custom strings, tune, and your bow will come back faster than what you sent it (not sure how he does that) it becomes a more attractive proposition.

Davidmil brings up a good point about the tuning with bow in hand, but that is more form coaching. All the same it is critical for getting a consistent shot. The best tune in the world won't help you you aren't consistent.