Beware Fraudulent Buyers Bearing Cashier's Checks

Hi, Someone recently tried to scam me and I don't want it to happen to others.
There were many emails back and forth, at first sounding very legitimate, but in a nutshell... Someone emailed that they wanted to buy one of my paintings. They asked if they could pay by check and were in a hurry because it was an anniversary gift. I replied that I couldn't send anything until the check cleared my bank. They said fine and asked for my address to send the check. They said they worked as a ship engineer in the Atlantic and had a stateside agent who would send me a check. Sounded weird, but they provided details that seemed personal and plausible enough. Yesterday I received a cashier's check, but it was for $1700+ more than what the painting cost. I emailed why so much money and she (he?) said they'd send an address where I could send back the excess. I'm skipping some details here, but you get the gist. I called the bank that supposedly issued the cashier's check and they said the check was fake. I Googled the return address on the envelope and it didn't exist. I called the law firm listed on the return address and they said others had called and it was a scam, that they would never send checks and don't use that bank. My bank said that if I'd deposited the check, that it could come back in days or weeks later as being invalid, and that it might appear cleared when it wasn't. The scammer must hope that it will take a while for the check to come back as fake and that you'll send the money beforehand. I'm out about $80. for a mat, backboard and shipping box that I'd ordered for the piece before things got weird. Don't let people pay by check and definitely contact the issuing bank to see if the check is valid, even if it is a cashier's check. Good luck out there!