Depends on what the favour is, how hard it is to obtain (taking into account the way this system works) and how important it is to you or your wellbeing.

Fo administrative stuff, anywhere between 50€ and 200€. For medical stuff, usually a lot higher. I had to bribe the doctor that was leading my wife’s pregnancy to get “extra care”. Basically, she doesn’t throw you under the rug like the rest of the patients (quick checkups, reschedules checkups quite frequently, does a 30 second ultrasound, done deal) and really takes care of the person in question and the baby. That cost me 500€. It may not look like a lot to most westerners, but for comparison 500€ was my monthly salary at the time. So, yeah, that is expensive for people that live here.

Other procedures like surgeries usually cost a lot more. Depends on the surgery and how complicated it is, so anywhere between 1K€ and 15, 20K€. Again, this is expensive for our standard. People usually sell aprtments or houses in order to cover these “bills”.