Check, paypal, USPS money order, cashiers check, even cash (fake bills) you can get scammed. Even wires can be undone (hard, but doable). Focus on the person first, and then the payment method.
This is why you should deal with people you can identify and trust based on: (i) feedback and on ebay (send seller a message and wait for response to confirm the person is who they say they are); (2) job -- ask for work email address; (3) where they live (google the house you are shipping to -- does the name match and does the check matche and is the house in a nice area where someone would have the money to buy 4k worth of stereo equipment); (4) google search of real name, email address and username -- lots of hits = good.
All that being said, you can check your jurisdiction's UCC and banking laws and find out exactly what your rights are. To get them, you often have to jump through hoops, but they are available.
One last point, think of who YOUR bank or financial institution is. I use a credit union because, in part, their policies are such that once a check clears, they do not permit another bank to issue a stop payment. I know some banks intrabank and interbank, will.
