Yeah, this is a huge problem with E-Bay and other web-sellers. Here is a story you may wishh to read so this does not happen to you.
I have a friend (really, it was not me) who listed his 25th aniversary Mustang convertible (in desperate need of some TLC) on the web and he got an e-mail that ended up being the reverse of the sting you have brought up.
A "buyer" contacted him via e-mail, (the only way he could be reached reliably due to his very full schedule and constant travel) to say he would buy the car, full price, but needed it shipped to England.
He sent my friend a Bank of America cashier's check for the car plus shipping, total of $10K, ($5K for the car and $5K for the shipping.) Buyer asked the seller to send his (buyer's) shipper company a check for $5K and make arrangements to have the car shipped at his convenience to the new owner in England.
My friend deposits the check into his bank, not BofA, and is assurred it is a good cashier's check. He then sends $5K via Western Union, to the company the buyer provided as requested.
Of course, a couple of days later, he learns from his bank the cashier's check was counterfeit and worth 0. He is now out the $5K he sent off via WU. Of course there was no shipper and he still has his car. He contacted the police, they were absolutely worthless and did not care one bit. He tried to contact the FBI and they could not be bothered either.
He presently is pursuing small claims against his bank as they assurred him the cashier's check was solid gold. I can't wait to see how they try to screw him in court - he should actually win and get his $5K from the bank as he relied upon their representation, and they are in the business, to his detrement.
To make matters worse, he gets another exact same scam about 1 month later where he e-mails with a "buyer" and they send him another $10K check. Same thing, this time ship car to New Zealand.....
Having been burned once, he did not fall for this one. He forwarded all the information to the police, he was very careful not to handle the check, thinking they may want to process it for fingerprints, and they again said they could not be bothered. (I am sorry, remind me again why we pay all these redicilious taxes???)
So, just a word to the wise, if it seems to good to be true, it usually is.
That is my free advice for the day.