Friends of ours have one mumofmadboys - it seemed to me like a kind of upmarket time share but I am not sure how it works. When we stayed with them at one we found the place lovely, quiet and peaceful and very much enjoyed our stay.
I don't know how much they paid for the bond but then you have to pay a fee for staying in a property too, plus flights if going abroad. Our friend did mention that the popular places get booked up as soon as the season starts and you can be hanging on the phone trying to book somewhere only to be disappointed. However, they are very keen, although it did not tempt us when we thought about it afterwards.
Hope that helps. 