I think Barjohn has the best suggestions above for protection.
From the original post I am not sure why everyone thinks its a scam. The guy sent money via pay pal why is that suspicious ? I have been using Pay Pal for years . Sending it through friends and family saves the commission but the buyer loses protection which is the only thing thats strange. I wouldnt say for sure its scam. I also wouldnt say for sure its a stolen CC on pay pal as I am not sure its that easy. That being said I wouldnt send my expensive gear out with only a down payment . Do the full transaction through Pay Pal and you have protection but get the whole thing paid. He too as the buyer has protection by paying all through paypal
Freight forwarder means nothing if the guy is abroad. Not sure why that is a red flag to some. I have done millions of dollars through freight forwarding companies in my lifetime in technology. If the guy is not abroad no forwarder would be needed.
Get paid one way or the other in full before releasing any product