$300 seems to be the median going rate for "B" service. You don't HAVE to do the "B" service if you don't want to. For example, you could replace your own wiper blade inserts, change your own oil, check your brake fluid, check your horn, aim your own headlights, reset your own FSS counter. IMHO, the "A" and "B" services are only to get you in the door so they can inform you of repairs which need to be done to your car. On the upside, some dealers discount the labor on regular maintenance items like brake pad replacement. This can result in savings of up to $150 for brake pad replacement (on the ML).