Here are a few places: http://www.baumtools.com/ http://www.techni-tool.com/ http://www.asttool.com/
The last site is mainly about their scanners but they are one of the oldest German Secial Tool suppliers.
Special tools also can be purchased through your MB dealer (often at competative prices). The only problem will be that you HAVE to have the tool number as the parts department has no way to look it up without having the service dept give them the number. This is difficult to arrange.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician