A pro-fit.
I felt like an utter tool walking out of Nate Loyal's fitting studio, $180 poorer with only a little business card with my measurements scribbled to show for it. The end result of nearly 3 hours?: my cleats were shifted a few mm and my saddle up and back a little. And he gave me some advice about how to sit on the saddle and work on my core & back muscles.
But then my chronic knee pain magically vanished. I cancelled the appointment with the knee-surgeon (which could easily have cost 20 or 30 times what the pro-fit cost), and was able to ride longer and faster than before--even faster than when I was in my twenties when I was dumb enough to instead spend that money on sew-ups and the latest Oakley sunglasses.