In the Netherlands it depends on the how popular the event is I guess, talking about tour rides not so much races as I have no experience with racing.
Tour rides organized by ‘local’’ clubs tend to be 10 to 15 euro max, if they are more expensive usually a part of the fee goes to a charity.
Tour rides that are organised by a promoter/company are usually a bit more expensive but you can buy a season pass for all their events bringing the cost per event down.
And then you have the big tour rides like Amstel Gold Race, those do cost more but not like 100 EUR, then again those are massive events.