gift giving

FH and I were invited to a wedding, but for several reason aren't going. We want to send a gift but don't know what exactly. We looked at the registry (at least the only one I can find her for) I don't know if she had a bridal shower and if she did I wasn't invited so I didn't actually know where she was registered. So I looked at the registry and there isn't anything i really want to send her from it. Her list is very short.
I was thinking of sending her an american express gift check but I'm not sure for how much.

How much do you normally send when u don't attend the wedding??

We aren't very close with the couple. I'm friends with the bride, but I haven't seen her in at least a yr. We have only spoken via
e-mail and rather infrequently.
I don't know the etiquette on this.

I would say $50 or $75 IMO.

ETA- OR

I think the gift checque is a great idea! You could also send her a gift card to the store she registered in. $50-75 sounds like a decent amount, but again, give what you can. And you don't have to send something, but it's a very nice gesture.