well, heres how we had it figured out for our 'group":
we put it on whoevers insurance is already the lowest, and we only put liability on it, and when you buy the car, you have to, along with you recipt, submit the original add where you found it. if the add states that the car is $900 and you show a recipt for $300, then something in up with that. BUT, if you and add for $900 and the recipt says $700 then i think thats perfectly reaosnable. we’d also have to use the honor system here as well.