Tam, I have had a similar situation in the past, ending in a small claims lawsuit.

It is a no-win situation for you - IMHO the more you try to accomodate someone in this situation, the deeper you get and the less likely the outcome in your favor. Clearly state your position (in writing) to the other party, document with photos, return the plane with a "signature required" delivery (at your expense, if need be), and write off the experience.

Sorry to say, there is not a lot you can do to force the other party to pay up for storage costs, or even return shipping expenses. Nor can he force anything from you, unless he is willing to spend a considerable amount of time and effort (given the distance, not likely). However you do have a legal obligation to return his property. Just cut your losses and refuse to do business with the other party in the future.

Barry