(CBS) Jeff and Shawn Mosch were looking to sell their '61 Buick special.

So when they got a buyer, they were delighted. But as CBS News Correspondent Mika Brzezinski reports, the buyer was in Africa. That left the couple a little leery of his payment plan.

"Basically he told me there was a person in the states that owed him $8.800," said Jeff Mosch.

To make things easier, the African buyer said he would have that person, who was in Pennsylvania, send the $8,800 directly to the Moschs in Minneapolis. They would deduct the price of the car, $1,600, and then send along the balance to the buyer in Africa -- $7200. Sure enough, a cashier's check came in the mail.

But Shawn wanted to be sure, so she went to the bank and said, "I need to know when this is going to be a good clear check. When this is going to be actual money I can spend and it's never going to come back and bite me in the butt."

And she was told, "24 hours ma'am, no problem."

Feeling reassured, the Mosch's wired the balance to their buyer.

But a week later, the check came up as counterfeit, and the Mosch's were left holding the bag.

"$7,200 ... that's a lot of money," says Jeff.

The scammer was taking advantage of not only the victim but also the banking system -- specifically, the process by which checks are cleared. The con artists get their money before the banks discover their checks are bogus.

Susan Grant, with the National Fraud Information Center, cautions, "Just because the money is available for you to use doesn't mean the check is good."

That's because when a check is deposited, a bank first makes the money available to the customer, often in one or two days. After that, the check is sent back to its original bank. Only then is it verified -- which could take weeks.

The bottom line: if the check is bad, the burden is on the customer.

Nessa Feddis of the American Bankers Association says, "Customers, when they accept a check from a stranger, they need to exercise some caution."

And lots of it, because this scam comes in all shapes and sizes and is spreading throughout the country.

As for Moschs, Shawn says she feels more anger towards the bank than the scammer.

The bank told them today they have to pay up. And the car?

"It's still for sale, but cash only," they say.