Exhaust gas analyzers are fairly expensive as single test tools go. By what they do they are comparatively more money than the 20K scanner necessary to do real diagnostics.
But even more important is the fact that modern cars without test ports (almost all MBs) can not be adjusted properly with such equipment. BUTTTTTT, as I have posted maybe a thousand times, proper mixture can be adjusted through on-off ratio or EHA current with a $30 multimeter. READ!!! the DIY article I wrote on evaluating engine controls. This can be done for less than thirty dollars and some knowledge.
Bosch Master, ASE Master, L1
33 years MB technician