Ok, this is entirely imagined by me, it could already be posted, fixed, unworkable, etc...BUT here goes.
You have a Krol Blade (item is an example)...you find another one in the AH extremely overpriced. You ask the seller to send it to you CoD...leave it in your mail when you get it. THEN...let it sit stagnant until the return date. The day before the return date, send YOUR Krol Blade to them CoD for the same price, and use whatever the return statement is...not sure here. Maybe, just MAYBE, they will click the item, initiating payment for it, and you make the money, later they get their Krol Blade back and you sell your epic for extremely high amounts of cash.
Granted this may not work, if you have any tweaks to make it work or make it effective, add them here.