It happens all the time. It's called a PRINTER. Anyone could print a check. You can buy MICR printers at ease. Not all checks have security features and we see more fake Cashier's Checks then anything else.
Because the trick is...most of the time...you either have to A) Send them part of the money back after the "check clears"...or B) Use the money to "buy stuff from them"...which is what is going to happen in your case. You deposit the check...you buy something from them...they jump ship with the funds you spent with them...and then the check returns on your account and your not only out the money you spent with them...but the entire amount of the check as well.
The CIA doesn't deal with petty check forgeries, they have bigger fish to fry than small time crime like that. With the economy in the shape it is in, it has been increasing more and more since I got into banking over 5 years ago. Probably 10 fold. Hence why most people don't even take checks anymore...because they don't want to take the risk. Your thinking local police, FBI, or Secret Service that deal with check forgery. We have no real dealings with the CIA. In fact we deal more with the S.S. with fake money than we do with any other form of law enforcement. People get away with it daily and it is wrong. Plenty of people suffer from these "legit" scams. Checks look real. Some even have security features, such as color changing paper and heat activated portions that dissappear when you rub them or breathe on them. Different times, smarter criminals. But don't take my word for it, your on the internet a lot. Go google it.