Well that sucks.
It would be good to have a hard copy inventory of what you sent him, when it was delivered, serial numbers and details of what each part was. Call the attorney generals office of the state he is in to make a claim against his business with the inventory list you have. I would expect there are issues with taxes, fees and whatnot that are parallel to the issues his customers are having. Know anybody who lives in the area? A knock on the door can work wonders, I know of a few instances where that is all it took to get things square.
Really crummy situation to be in. Good luck.
Best,
Ted
