I'm only invited to the evening. That's fine, I didn't expect.to be invited at all, lots of friends are going, it's local, it will be a fun party.
However, on the assumption that at most there will be a finger buffet and I'll be buying my own drinks, I'm not sure I would have given cash. Maybe a bottle of something for them to enjoy later.
There's a note in with the invitation along the lines of your presence is most important but....we'd like cash towards honeymoon.
I've no idea what would be an appropriate sum. It's just me(not a couple).
If it makes a difference, couple are middle aged, 2nd time for her, first for him. They and majority of guests are, I'd say, affluent end of working class.