It's a Scam!!!!!!
Taken from the State Department Federal Credit Union's website:
http://www.sdfcu.org/news/topics/scamarticle.pdf
The setup is simple – You place an ad on an online auction site selling an old
treasure. A few days later, your item is sold and you receive a check for more
than what you should be paid. Simple mistake you think- I’ll just cash the check and refund the difference back to the buyer. As you wait for the check to clear, you have already sent your item to the buyer.
Doing this could cost you greatly. The check that was sent to you was
counterfeit and now you owe your financial institution the entire amount of the check.
The scam artists, usually from overseas, typically target online sellers of
expensive items, such as cars or antiques. In a variation of the scam, consumers have received calls telling them they have won a large prize and telling them to remit part of a cashier's check to pay “expenses.”
The moment you are asked to send money back to a buyer, you should be wary.
Phony buyers sometimes offer explanations for the cashier's check being greater than the purchase price. The purchaser may claim the check was mistakenly made out for a greater amount, is a refund from an unrelated transaction, or includes transportation or import/export fees that need to be refunded. The scam artists typically ask the seller to wire money to a foreign country.
• Be wary of prospective “buyers” who send e-mails from overseas, want
to pay more than the purchase price , or ask pay by cashier's check but
then cancel the transaction and ask for a refund.