This is true, plus sometimes other parts as well - you might scare him off of servicing reps entirely.
I would say start him off slow, servicing ETA reps and Asian 7750s - probably a popular package of teardown, clean, reassemble, relube and adjust. I'd pay $200 for a well done job.
After he's used to doing repair by mail order and used to working with reps he can expand the services as he feels comfortable.