it sounds as though you made a very substantial contribution (emotionally as opposed to the financial one)to the most important day of their lives, this is what they're going to remember you for, the food processor would have been at the back of u dusty cupboard in a few years, but memories of the day and the stag and hen nights will be laughed about for the rest of your lives. if it was me, i would probably leave the exact same present on their doorstep on their first anniversary (ensuring it doesn't get stolen obviously, i would ring the doorbell and run away), that way the unfortunate loss is turned into something humerous, they will be incredibly touched that you have remembered their anniversary and you dont have to find the moeny for it before xmas. in the meantime let the guilt go and enjoy planning their anniversary suprise. :-)