$50 for somewhat called friends
$100 for real friends seen regularly
$0 for relatives because my parents are going to do it.

I only give money to groom or bride because the reception people can't be trust.

I heard more than once the money gone missing after the reception people took it.
Come on man, this is not being cheap! I am sure the groom and bride pay around the same amounts when they attend other people's wedding.