I went to a very similar ceremony a couple of years ago ... they too mentioned 'no gift required as our being there to help celebrate & share their special day was our gift to them' ... and on the invitation was how much $$ per head which helped as a Guest so much as then i knew how much to expect to pay at the end of the night ... and it worked out cheaper than i would have normally have spent on a gift

On their invite after the per head mentioned cost was what was included eg, beer, white & red wine, soft drinks, entree & main meal & dessert (which was the cake) ... Which made the per head sound such great value as you knew what you were getting