I've noticed over the past few years that billeting is in decline.
Its not just the number of people willing to take in billets (remember, your natural limit is the number of people you can fit in your car to and from the fields - not the number of beds and bathrooms, which frisbee players can go without), but its also the number of people looking for a place to stay.
While on the one hand, I think this reflects the increasingly improved organisation of Ultimate teams and tournaments (ie these days teams are more likely to organise group accommodation - which of course helps cement team comraderie (although at the expense of more work for team managers) I think overall this is a sad thing.
The beauty of billeting is the brotherly (sorry - can't think of an equivalant gender neutral term) nature of it. You're staying with someone you don't really know, or someone you don't really know is staying with you. But you're united by your love of Ultimate and the bonds of friendship that run through the Ultimate community.
Of course, this is not to discount the cost-saving that comes from staying with someone when you go to a tournament elsewhere. Not just the cost of a motel room or backpacker, but the cost of not having to eat out and not having to pay for taxis/buses/trains/hire cars/parking. Then there's the benefit of having a guide to show you how to get things done in the place you're visiting.
For having someone to stay - it builds the tournament experience for you, and perhaps more importantly, you've got automatic new friends and place to stay when you visit their towns!
So get into billeting - its good for you and good for everyone.