It seems like everybody wants to replace the hub assembly rather than exchange the bearing. I went through that on my Toyota recently. I bought the OEM bearing from a dealer for $70 and a guy air chiseled out the old bearing and pressed in the new one. I stood there and watched him and it was a tricky job. The hardest part was removing the ABS sensor from the wheel so he could take off the hub (20 year old car). Total cost of job was about $200. It would seem this is possible on our MBs too.