Ignition control module(EZL) or idle control valve? A price like that, if the exchange rate is what I think it is, would have to be the EZL, which indeed are prone to failure in your car. Even then the price is ridiculous. There are several EZL rebuilders in the U.S. In any case you should subscribe to EPC, which is either $3 a month or free, not sure now, and find out exactly what part your car has. Could be a different setup than the U.S. If possible it's nice to be able to swap out the EZL with another car to make sure that's the problem. Here are some hopefully helpful links.
Idle Control Valve:
Your Parts Search Returned 1 Part(s)
EZL Rebuilder:
Mercedes Benz Accessories
MB Electronic Parts Catalog:
EPC online