mmmmm, now that's interesting to just be invited to the ceremony. I would probably just all pool together for something small - i would think $10 each would be sufficient. Maybe even give it to her on her last day of work before she gets married then that way she knows its from you all at work and also because there isnt anywhere to leave the gift at the ceremony, you usually pout the gifts at the reception. If you were invited to the reception then obviously that would be a different story.