I have bunch of expensive used clothing to sell and I know a guy who is a high ranked seller on ebay and Amazon. I asked him over the phone whether he can sell them for me for a fee if I ship them to him. He said he can. I really trust this guy but technically if he ever decides to run away with them there is nothing I can do. I think I need to get some sort of a written guarantee of payment but I am really hesitant to do so because it would look like I am suspecting him. What should I do? Is there a polite way to ask for this?