That seems like it is way over priced. I replaced the wheel bearings on my E30 (DIY) and the procedure is pretty much the same for any 3-series. It is a bit of work and takes some special tools. It requires removing the half shaft and pressing the bearing out of the hub and pressing the new one in, then pulling the halfshaft back into the hub.
I bet any decent BMW Independent shop can do this repair for you at half the price. Shop the job around if you have a few Indy's to choose from.