Eloping Invitations

Me and my fiance have decided to elope since our families live in different states. We will be having a beach wedding in the caribbean. It is no surprise to our families since we let everyone know ahead of time. We have also let them know it is "open" to whoever would like to come, knowing it`s not probable that anyone could afford it. Now we want to make it official and do a "beach style" invitation. How can we word it so it doesn`t sound "tacky", that everyone is welcome (if it`s in their budget).??Help, Please....