Just attended the wedding of a friend
quite standard church wedding+dinner party
The organiser told us it seems less than 20,000 euro.
He call this a standard wedding. Neither too cheap nor too expensive.
As a guest (not relative), per person may give 30 euro as contribution.
You can prepare a wish list, otherwise just hope to receive some money.
The gift we get is a cute wooden fan, very dedicate but wouldn't be too expensive.