I am having kind of the same issue. It is actually all my friends who live overseas and still live with their parents (buncha losers, but I love them lol) or simply think they can't afford it. It is a little bit costly, but not impossible to pull off.
So I would suggest to put together a presentation with a bunch of enticing pictures of the beach, the hotel, all the stuff you can do there; find out the rates, and really try to convince them they want to take a vacation there, relax, and while they're at it, attend you wedding. It is my strategy and I hope it works.
Trust me, after they come back home, they'll be raving about it for days on end. I'm still raving about a DW in Mexico I attended in February. I did not even know the couple lol.
I think the money I spent on that wedding is so much more worth it than what I will spend to attend a local wedding next July (dress, shoes, present, etc). That being said, of course you wanna make sure a DW is really what you want.