Does the Couple Pay for the Guests' Travel Expenses?

The bride and groom are not expected to pay for the travel expenses of their guests.

Accepting an invitation to a destination wedding means you, as the guest, understand the financial responsibilities and will be able to meet them yourself. However, it is proper for the bride and groom to arrange discounted group airfares through a travel agent and keep guests informed of any special promotions. That information is usually included in the invitation and sometimes with the save-the-date cards, but if it isn't, or you'd like to book your flight way ahead of time, just ask the bride.

Find any couple's registry here.
Read more about destination weddings:
How can I find out about travel deals?
What's the proper guest etiquette for a destination wedding?