How about a freeper lottery. We each pitch in what we can, then according to how much we pitch in, That money goes into our Freeper bid. If we win, then one lucky Freeper gets to go. That Freepers name is pulled out of a hat that has a ticket for each person who puts money in the pot. Maybe even have it where the more money you put in the pot, the more tickets with your name on it get put into the hat... I am almost a tiny bit serious...
See #19. The winning bidder gets to select four friends to come along for the ride.