I second the caveat that Bruno mentioned around amounts varying across firms and across countries regions. However I never came across an office or a company that doesn't pay referral bonus for consulting staff positions (my direct and indirect experience being across all three MBB, and having worked with people from offices in 7 countries in Europe + US).
Usually for entry level positions bonuses are less than/around a thousand Euros/Dollars, for more senior position they can go up to mid single digits.
As mentioned, if the name of candidate is already part of "funnel" (e.g. target school, met at an event, etc), bonus is not disbursed.
Hope it satisfy your curiosity!