We have stocked the fluid under a MB number for a similar cheap price. The fluid can be sourced through Febi/Bilstein or Pentasin brand name. The same fluid is used on BMW and Audi systems, but there is more than one formula. We also stock a very similar fluid for Jaguars and RR that comes from Castrol. I think its the same as the Febi product that we buy under a MB number(don't have the number at home), but we stock both as I know of no printed standard.
Bosch Master, ASE Master, L1
33 years MB technician