follow exactly what they did on another scam.
Tell him you can't wire him any money, but you have something valuable (jewelry, gold) that you can send him. Then send him a box of rocks, but make a declared value of $8,000. He'll have to pay a bunch of $$$ in duty (depending on his country) and he'll get the box full of rocks.
Don't bother sending this to the authorities, I don't think (and I pray) that the governmment doesn't waste it's time going after these types of scams.