I've had three over the last decade, ranging from $200 to $350, not including new parts.
The first in 2008 didn't solve Achilles pain, but I learned my saddle was too low.
The second in 2014 (retul with very experienced coach) didn't solve my main issue, back pain. But retul confirmed my knees already tracking perfectly. Ok, so what?
The third, 2016 with a biomechanics PhD who came to my home (cool), didn't solve knee or back pain. But my right leg pedal stroke was smoothed by moving cleats all the way back.
So, mixed results. Don't expect miracles.