Are parts usually this expensive?

The car self starter died in my car, the technician said tte part costs 850 sar (266$) my car is a geely 2017 emgrand x7, here is a picture of the self starter:

He also said the spark plugs needs to be changed which costs 150 sar (40$).

Where can i buy legit parts online? Or how can i know a good part from a rip-off?