Some folks collect coins, some collect rubber bands, while others find joy with Beanie Babies. I collect large amounts of money.

Sure, you're thinking, we would all like to build a collection like that. I'm currently up to $73,750, and I use it in my classes when I teach computer security.

There is a catch, of course. It's all fake money, sent to me by scam artists. Let me walk you through my latest piece, a cashier's check drawn on the National Bank of Texas, from the branch in Fort Worth.

I sell a lot of stuff on eBay and CraigsList. I had a car dolly posted on CraigsList, with an asking price of $525. I received the following email the next day:

How are you today?....i saw your item listed on craigslist,i just want to know if the item still for sale and the last price you are going to sell it.please get back to me asap.Regards.

I see a lot of emails with terrible English skills, which is a topic for another essay. I didn't see any red flags yet, so I replied that I still had the tow dolly. An hour later, another email arrived, copied verbatim below:

The payment would be sent by UPS courier company and the item will be picked up as soon as you receive my payment,I will wait for the payment to get cashed before i'd send my shipper for the pick up.I will like to tell you that i would be sending a certified check worth of $3200 to cover the shipment of the item and the money for the item.As soon as the certified check reaches you,have it cashed and remove your money for the item and send the remaining fund to my shipper by western union money transfer.My shipper is also picking some of my other items up for me in the same city of yours so that is why i need to give him that amount.I will like you to remove $100 for your running around in getting the money orders .Please let me know if i can trust you on this so we can move forward from here. Regards.

The red flags went up. First off, this guy was going to send me a payment via UPS. Do you know anyone who sends a check by UPS to pay for something they found online? These scammers avoid sending anything via the USPS because it becomes a federal offense.

The second, and biggest, red flag was the amount. If you wanted to buy something for around $500, would you send a cashier's check for $3,200, then tell the seller they can keep an extra hundred for the trouble of cashing a check and calling someone?

I told him to send the payment. Two days later, I received an overnight UPS Express envelope with a cashier's check for $3,200. This one is actually well done; it has the bank watermark on the back of the check. I called the bank, and verified it was a fake.

Now, you must be wondering how the scammer 'gets' you. This is how it works:

They send a check for well over what is due. You are supposed to cash the check, which almost every bank will do, immediately releasing the funds because it is a secured source. After you have the cash available, you send their 'shipper' a payment, usually a couple of thousand dollars.

Two weeks later, your bank kicks back the check, and debits the amount from your account. You're out the money that you sent via Western Union to their shipper, who is typically in a foreign country. In this case, the scammer is in Nigeria. I was able to trace him from his email. He would have pulled the funds from a Nigerian office of Western Union, and I'd be all the poorer.

Because I deal with these scams on an almost daily basis, I know what to look for. Hopefully, you know the red flags now. I get them to spend their money on overnighting a check, which takes a lot of time and effort to create. I collect the checks and money orders, which make a powerful statement when I pass them around the classroom. Who wouldn't mind holding in excess of fifty grand in their hands?

I always contact the issuing bank to make sure it's a scam, and to let them know that their cashier's checks have been compromised. Some scammers steal real used checks or money orders, remove the ink from them, and then print over the new blanks. This way, they have a real watermark.

The scammer is counting on one important sin: greed. You'll get your asking price, plus extra. Sounds like a great deal for the seller. Unfortunately, the old saying is accurate: If it's too good to be true, it probably isn't.