Love / Appropriate Wedding Gift for a Polish girlfriend of several months? [37]

I am an American who has been friends with a Polish girl for several months (email friends only through work-related circumstances). We've never met before, but I have gotten to know much about her and the culture of Poland and would one day like to visit. In the meantime, she is going to be married in a few months and I would like to send a wedding gift to her. My question then, is it culturally acceptable to send money as a wedding gift? I don't know the culture there that well yet and do not want to be insulting, so I thought it would be prudent for me to ask this question first. I could send something besides money, but not knowing, obviously, what she needs/wants, etc, I would hate to spend a lot of money on postage for something that she neither needs nor wants. Can someone please give me direction in this?

Thanks so much and I do look forward someday to visiting Poland as a tourist. From what my Polish friend there has told me, I think that I would like your country!