Years ago a person was being scammed by a Russian who wanted to buy his notebook computer. The Russian sent a money order, unsigned, and said he'd send a replacement but 'please send notebook, I need it for college'. By this time the seller knew he was a scammer and decided to play along. He sent some books which weighed the same as the notebook. But the seller told the Russian, "Sorry, I made a mistake. I sent the package and forgot to not mention it was a computer. So you'll have to pay $200 duty on it. You can take it out of what you owe me."
"Best Revenge Ever." - Comic Book Guy "The Simpsons"