Here's what you do.
Prosecute the transaction as fraudulent with eBay (safeharbor) and PayPal: as if the guy didn't send you anything and just ran off with your money. What you describe is a crime. Pursue it as such.
Hey sorry to bother you. My name is King. I bought waves mercury for half of the store price off of craigslist and the person scammed me out of my money. Gave me the program + ilok key. and there was no license available. Im running an apple mac and protools and garageband. Is there a way around this. Please assist me Im a college student and I spent my only tuition money thinkin I could make it back by charging at my studio. Thanks dude