I am going to go with what some others said, if you are that concerned about it then get refundable tickets, or see if the airlines has the cancel for any reason with their travel insurance. You are not going to find an insurer that is going to sell you 'cheap' travel insurance that lets you cancel out with them on the hook for any reason, and I think the closest you would get is a difference pay out, i.e., they give you the difference in the change fee, or maybe a fare difference to rebook but surely not the entire cost of the flight.

-Patrick