When it comes to rotating electrical Bosch rebuilds there own (I think). It is almost imposible to buy a new alternator or starter. The typical sale is rebuilt either from Bosch through MB or from Bosch through AutoZone.
We use almost no rebuilt products. The exception is rotaing electrical. I was checking an alternator for a 95 E320 yesterday and the MB price for a Bisch rebuilt was around $250 (I actually forget the amount). The new version was over $700. It was in the price sheet so I guess it was available.
Bosch Master, ASE Master, L1
33 years MB technician