ECS sells service kits here....
https://www.ecstuning.com/BMW-F10-52.../Service_Kits/
Yes, front and back can be had for <$500. These are quality Zimmerman rotors and PAGID pads. I don't know anything about the Holstein brand of sensors; however, they are probably good to go.
You may want to post your query in the California forum. Also, use Yelp to find a reputable indy.