Some more expensive machines are extremely expensive to maintain. My suggestion is that higher-tier machines should require less of the expensive ingredients involved in making that machine than cheaper ones. Another suggestion is that a reliability parameter for machines could make this more balanced.

Hi, to some extend, it is intended that expensive machines are also expensive to maintain. But i understand, that expensive machines maybe buffed a bit to reduce this effect.

The first way, calculating the "quality" out of ingredients and their value, is extremely difficult to implement and not very precise.
The second approach, to give machines some kind of reliability parameter is better suited for this. I'll test if this works.

Thanks for your response!
The problem with the reliability parameter however, is that I do not see a way for mods to automatically work without needing a configuration file of their own.