Thanks to everyone for your advice. We really appreciate it. The couple IS registered at two stores. I think registry is kind of a strange thing, and I'm not really sure the couple would actually USE everything they scanned into their 'wish list'... As far as WE know they don't enteratain formally, yet their list includes fancy crystal and charger plates and stuff like that.
So, in the end, we decided to go with the gift card thing (from one of the stores at which they are registered). Now THEY can decide if their 'gift' from us will be something that they really want and can use or whether it just looked nice when they were going through the store with the scangun (I guess that's how they do it).
The card will be hand delivered along with a note congratulating them AND expressing our sadness that we will miss the actual wedding
Thanks again for your advice.