There is a fair price for these things and in my opinion a lot of overcharging goes on in the bike industry.
Some of the workshop charging looks more like the motor trade. The techs are often paid a pittance.
As a beginner I took my bike into my lbs to sort out shifting problems. Was a simple issue – rear gear cable change. Guess how much they charged? £80 because the technician struggled with routing the internal cable.
Six months later, I attempted to do it myself. Very little experience, no technical ability – it took me less than 30 minutes.
I’ve now bought the tools and do most things myself.